* Add revert reason to EnumerableSet.get.

* Rename EnumerableSet values to keys

* Rename get to at

* Add changelog entry

* Rename keys to values

* Add leading underscore to struct members

* Add IERC721Metadata implementation into ERC721

* Add IERC721Enumerable into ERC721

* Update ERC721Pausable and ERC721Burnable

* Delete ERC721Metadata, ERC721Enumerable and ERC721 (now ERC721)

* Update mocks

* Update tests

* Update contracts/token/ERC721/ERC721.sol

Co-Authored-By: Francisco Giordano <frangio.1@gmail.com>

* Make ERC721Pausable and ERC721Burnable abstract

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

Bumps [acorn](https://github.com/acornjs/acorn) from 6.4.0 to 6.4.1. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/6.4.0...6.4.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* Upgrade to latest solhint rc

* Add private-vars-leading-underscore linter rule

* Add leading underscore to GSNRecipient constants

* Remove leading underscore from ERC165Checker functions

* Add leading underscore to multiple private constants

* Fix linter errors in mocks

* Add leading underscore to ERC777's ERC1820 registry

* Add changelog entry

* Add signed to unsigned conversion to SafeCast

* Update SafeCast exception message

* Add test for SafeCast int to uint conversion

- Update SafeCastMock
- Add tests for SafeCast int256 to uint256

* Update SafeCast int to uint definition

Apply suggestions from code review.

Co-Authored-By: Nicolás Venturo <nicolas.venturo@gmail.com>

* Update test for SafeCast int to uint conversion

* Update SafeCast test after code review

- Change "downcasts" to "casts"
- Move test closer to its function

* Fix error in SafeCast toUint256 description

* Fix breaking error in SafeCast

* Add uint256 to int256 conversion to SafeCast

- Add function
- Add mock
- Add test

* Update SafeCast unsigned to signed conversion

- Update error in conversion to be more clear
- Update constants in test to be powers of 2 instead of shifts

* Add changelog entry

* Update SafeCast tests

- Add minus in INT256_MIN for clarity

Co-Authored-By: Nicolás Venturo <nicolas.venturo@gmail.com>

Co-authored-by: Nicolás Venturo <nicolas.venturo@gmail.com>

Bumps solidity-docgen from 0.4.0-beta.1 to 0.4.1.

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [mocha](https://github.com/mochajs/mocha) from 7.1.0 to 7.1.1.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mochajs/mocha/compare/v7.1.0...v7.1.1)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [eslint-config-standard](https://github.com/standard/eslint-config-standard) from 14.1.0 to 14.1.1.
- [Release notes](https://github.com/standard/eslint-config-standard/releases)
- [Changelog](https://github.com/standard/eslint-config-standard/blob/master/CHANGELOG.md)
- [Commits](https://github.com/standard/eslint-config-standard/compare/v14.1.0...v14.1.1)

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* remove pass:normal from docs template

* add back pass:normal for auto links

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.1.2 to 4.7.3. **This update includes a security fix.**
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/wycats/handlebars.js/blob/master/release-notes.md)
- [Commits](https://github.com/wycats/handlebars.js/compare/v4.1.2...v4.7.3)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Nicolás Venturo <nicolas.venturo@gmail.com>

Bumps [acorn](https://github.com/acornjs/acorn) from 5.7.3 to 6.4.1. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/5.7.3...6.4.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* Make the sender the operator

* Make hook methods private

* Add changelog entry

Bumps [acorn](https://github.com/acornjs/acorn) from 6.4.0 to 6.4.1. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/6.4.0...6.4.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* Remove Address.toPayable

* Add changelog entry

* Make IERC721 contracts interfaces instead

* Bump minimum compiler version for IERC721

* Remove ERC721.burn(owner, tokenId)

* Remove ERC721._checkOnERC721Received from the contract's API

* Fix linter error

* Remove Escrow and PullPayment withdrawWithGas, replace for withdraw

* Add changelog entry

* Add reentrancy notice

* Remove Roles

* Add AccessControl and tests

* Removed IAccessControl

* Add RoleGranted and RoleRevoked events

* Make roles grantable and revokable regardless of their previous status

* Fix typo

* Add documentation

* Cleanup tests

* Add enumeration tests

* Add _setRoleAdmin tests

* Fix lint error

* Fix AccessControl link in docs

* WIP on access control guide

* Rename getRoleMembersCount

* Add tests for new role admin

* Make AccessControl GSN compatible

* Update access control guide

* Rename admin to adminRole

* Rename roleIds to roles

* Add 'operator' to RoleGranted and RoleRevoked events.

* Only emit events if the roles were not previously granted/revoked

* Uncomment expectEvent.not tests

* Rename operator to sender

* Add changelog entry

* Move Pausable into utils

* Move Strings into utils

* Move Counters into utils

* Move SignedSafeMath into math

* Remove ERC1046

* Make ERC20Snapshot.snapshot internal

* Move ERC20Snapshot into ERC20

* Add drafts deprecation notice

* Remove drafts directory

* Add changelog entry

* Apply suggestions from code review

Co-Authored-By: Francisco Giordano <frangio.1@gmail.com>

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

* Remove Ownable.isOwner.

* Remove ownable behavior from tests

* Make Escrow use Ownable instead of Secondary

* Migrate GSNRecipientERC20Fee to Ownable

* Remove Secondary

* Move Ownable to access directory

* Remove mentions of Secondary

* Add changelog entry

* Move Ownable tests to access

* Remove unused mock

* Remove ERC20._burnFrom

* Add changelog entry

Bumps [@openzeppelin/cli](https://github.com/OpenZeppelin/openzeppelin-sdk) from 2.7.1 to 2.7.2.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-sdk/releases)
- [Commits](https://github.com/OpenZeppelin/openzeppelin-sdk/compare/v2.7.1...v2.7.2)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [@openzeppelin/test-helpers](https://github.com/OpenZeppelin/openzeppelin-test-helpers) from 0.5.4 to 0.5.5.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-test-helpers/releases)
- [Changelog](https://github.com/OpenZeppelin/openzeppelin-test-helpers/blob/master/CHANGELOG.md)
- [Commits](https://github.com/OpenZeppelin/openzeppelin-test-helpers/compare/v0.5.4...v0.5.5)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [@openzeppelin/gsn-provider](https://github.com/OpenZeppelin/openzeppelin-gsn-provider) from 0.1.9 to 0.1.10.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-gsn-provider/releases)
- [Changelog](https://github.com/OpenZeppelin/openzeppelin-gsn-provider/blob/master/CHANGELOG.md)
- [Commits](https://github.com/OpenZeppelin/openzeppelin-gsn-provider/compare/v0.1.9...v0.1.10)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [acorn](https://github.com/acornjs/acorn) from 6.4.0 to 6.4.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/6.4.0...6.4.1)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Remove crowdsales from sidebar documentation, add links to old version

* Remove mentions of Crowdsales from the documentation

Bumps [solhint](https://github.com/protofire/solhint) from 3.0.0-rc.3 to 3.0.0-rc.5.
- [Release notes](https://github.com/protofire/solhint/releases)
- [Changelog](https://github.com/protofire/solhint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/protofire/solhint/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* Make ECDSA.recover revert on error

* Removed unused test

* Remove duplicate line

* Add tests for invalid signatures

* Fix linter errors

* Add changelog entry

* Use bytes32 explicitly for Create2.computeAddress(), to force users cache hash of the bytecode

* Remove only from test :)

In https://github.com/OpenZeppelin/openzeppelin-contracts-ethereum-package/pull/76, we are rearranging the erc721metadata contract storage layout, so the new variable is added at the end. This commit applies the same change to the vanilla contracts repository, so migration from 2.5 to 3.0 is easier for users using the transpiler.

Bumps [mocha](https://github.com/mochajs/mocha) from 7.0.1 to 7.1.0.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mochajs/mocha/compare/v7.0.1...v7.1.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [@openzeppelin/test-environment](https://github.com/OpenZeppelin/openzeppelin-test-environment) from 0.1.2 to 0.1.3.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-test-environment/releases)
- [Changelog](https://github.com/OpenZeppelin/openzeppelin-test-environment/blob/master/CHANGELOG.md)
- [Commits](https://github.com/OpenZeppelin/openzeppelin-test-environment/compare/v0.1.2...v0.1.3)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [solhint](https://github.com/protofire/solhint) from 3.0.0-rc.2 to 3.0.0-rc.3.
- [Release notes](https://github.com/protofire/solhint/releases)
- [Changelog](https://github.com/protofire/solhint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/protofire/solhint/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>