(cherry picked from commit dd6ec219)

* improve prepack script

* remove .npmignore

* make prepack use pkg.files

* fix linter errors

(cherry picked from commit cc19ccfd)

(cherry picked from commit fa004a7f)

* Fix transferFrom not updating allowance before calling receiver.

* Fix from being passed as operator.

(cherry picked from commit 2ccc12b3)

* Add requirement of non-zero from to ERC20 transfer.

* Add test for transferFrom zero address to behavior.

* Create ERC20.transfer behavior.

* Add tests for _transfer.

* Add changelog entry.

* Fix linter error.

* Delete repeated test.

* Fix hardcoded error prefix.

* Update CHANGELOG.md

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

* Address review comments.

(cherry picked from commit ad18098d)

(cherry picked from commit 3112c1b9)

(cherry picked from commit c92b7530)

* Moved ERC1820 related contracts out of drafts and into introspection.

* Moved ERC777 related contracts out of drafts and into token.

(cherry picked from commit c794c966)

* inline keccak256 result

* Update ERC777.sol

* switch hex constant style

* Update ERC777.sol

(cherry picked from commit e60c7904)

* Add ERC20 compatibility.

* Reusing ERC20 tests for ERC777.

* Improve documentation.

* Add changelog entry.

* Improved ERC20 behavior tests.

* Add revert reasons to ERC777.

* ERC20 methods allow sending tokens to contracts with no interface.

* Register ERC20 interface.

* Add comment about avoidLockingTokens.

* Improve revert reason string.

* Make ERC777 implement IERC20.

* Fix test revert string.

* Remove unnecesary require.

* Add private _transfer.

* Update contracts/drafts/ERC777/ERC777.sol

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

* Update private helper names.

(cherry picked from commit aa4c9fea)

* Hardcode ERC777 granularity to 1, remove tests.

* Add clarifying title comment.

(cherry picked from commit 376820d5)

(cherry picked from commit e287ea6f)

(cherry picked from commit af55a843)

(cherry picked from commit 67bca857)

* Error handling in ERC20 and ERC721

* Added message string for require.

* Fixed solhint errors.

* Updated PR as per issue #1709

* changes as per #1709 and openzeppelin forum.

* Changes in require statement

* Changes in require statement

* build pipeline fix

* Changes as per @nventuro's comment.

* Update revert reason strings.

* Fianal update of revert reason strings.

* WIP: Updating reason strings in test cases

* WIP: Added changes to ERC20 and ERC721

* Fixes linting errors in *.tes.js files

* Achieved 100% code coverage

* Updated the test cases with shouldFail.reverting.withMessage()

* Fix package-lock.

* address review comments

* fix linter issues

* fix remaining revert reasons

* Add a vault to PostDeliveryCrowdsale.

* Add changelog entry.

* Apply suggestions from code review

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

* Rename TokenVault.

* add solhint ignore directive

* Bump Solidity version to 0.5.7

* Add changelog entry.

* initial docsite setup

* switch from pushd to cd

* install and set up solidity-docgen

* use the docsite branch next for now

* make it clear that env var is a repository

* add a clarifying comment about a relative path

* change relative to absolute path in docsite script

* add docgen script

* add first few READMEs for contract documentation

* update solidity-docgen

* add docsite as dependency and adjust script

* update openzeppelin-docsite

* update solidity-docgen

* remove dummy text

* update docgen and docsite

* update openzeppelin-docsite

* add netlify.toml

* udpate tokens guide for 2.2

* add DOCUMENTATION.md

* Update docs/learn-about-utilities.md

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

* fix PaymentSplitter docs wording

* update solidity-docgen

* add missing ERC20 contracts

* update solidity-docgen

* trigger deploy with cleared cache

* update solidity-docgen

* update openzeppelin-docsite

* remove travis docs setup

* update openzeppelin-docsite

* switch to published solidity-docgen

* Create autoamtic release script.

* Add changelog update date script.

* Improve release scripts.

* Apply suggestions from code review

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

* Apply suggestions from code review

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

* Remove moment dependency.

* Fixes/Improves constants inline documentation.

* Fixed solhint error.

* Moved the comment before the variable

* IERC777 from specs, constants returned, up to defaultOperators. (#1159)

* IERC777 oprarator approvals (#1159)

* ERC777 oprarator approvals fixes and tests

* IERC777 send and receive with ERC820 (#1159)

* ERC777 Add burn functions and fix send functions (#1159)

* ERC777 Make expectEvent compatible with web3.js 1.0 (#1159)

* ERC777 Add ERC820 deploy script (#1159)

* ERC777 Complete implementation of ERC777 (#1159)

This implementation conforms to the current EIP

* ERC777 Update ERC820 Registry contract to final version (#1159)

* ERC777 Move contracts to 'drafts' folder (#1159)

* ERC777: Update to ERC1820 registry and linter error fix (#1159)

* ERC777: implement recent changes of EIP777 (#1159)

* ERC777 Fix formatting (#1159)

* ERC777 Update to solc 0.5.2 (#1159)

* ERC777 Fix travis CI errors (#1159)

* ERC777 Fix linter errors again... (#1159)

* ERC777 Fix unit test (#1159)

* ERC777 Fix unit test again (#1159)

* Remove extra newlines.

* Rename ERC777Base to ERC777.

* Remove 'Token' from contract names.

* Replace ops for operators.

* Move operator check out of _send.

* Remove ERC777Burnable.

* Remove ERC1820Client, now using the interface directly.

* Minor internal refactors in contracts.

* Delete extra test helpers.

* Simplified tests.

* Add basic 777 tests.

* Add granularity send test.

* Add first operator send tests.

* Add burn tests.

* Refactor send and burn tests.

* Improve send burn refactor.

* Greatly improve test module.

* Burn instead of send removed tokens.

* Add operator tests.

* Improve send tests under changing operators.

* Refactor and merge send and burn tests.

* Add missing and not-implemented tests.

* Make _burn private.

* Fix typo.

* Greatly improve tokensToSend tests.

* Refactor hook tests.

* Fix hook tests.

* Update openzeppelin-test-helpers and ERC1820 address.

* Fix natspec indentation.

* Make interface functions external.

* Remove redundant private revoke and authorize functions.

* Improved readability of if statement.

* Remove unnecessary asserts.

* Add non-one granularity test.

* Fix hook call order in _mint.

* Fix _mint not reverting on failure to implement tokensReceived.

* Remove special case in operatorFn when from is 0.

* Refactor ERC777SenderMock.

* Add tokensReceived tests.

* switch to updated ganache-cli-coverage fork

* Fix linter errors.

* Add mint tests.

* Fix linter errors.

* Fix tests.

* Update test/drafts/ERC777/ERC777.test.js

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

* Add changelog entry.

* removed unnecessary require

* build pipeline fix

* kept as it is

* Added require

* removing unused variables

* undeleting the _

* replacing all instances of from: anyone with from: other

* replacing all instances of from: anyone with from: other

* replacing all instances of from: anyone with from: other

* changing anyone to other

* changing anyone to other

* Update PaymentSplitter.sol

* add back private function docs

* add non-zero address requirement

* add comprehensive contract-level docs

* use capital E for Ether

This reverts commit 07fc8c73.