* replace readme badge

* remove travis config

* move to codecov

* add codecov config

* fix coverage running

* GSN basics guide (#1847)

* Fix linter error

* Initial draft for basic GSN guide

* Add CustomerAcquisitonCost link

* Review 'gas costs' phrasing

* Rename relay to relayer

* Apply suggestions from code review

Co-Authored-By: Santiago Palladino <spalladino@gmail.com>

* Improve transition to contract usage explanation

* Improve payment section phrasing

* Apply suggestions from code review

Co-Authored-By: Andrew B Coathup <28278242+abcoathup@users.noreply.github.com>

* Apply more review suggestions

* Add code

* Add unreleased warning

* GSN Docs Tweaks (#1860)

* Adjusts links

* Adjustments

* Update gsn.adoc

Fix typo

* Adjusts copy and links for GSN guide (#1865)

* Adjusts copy and links

* Formats links

* Adds website link

* remove attach_workspace

* leave default working_directory

* use npm ci for installing deps

* rename dependencies job

Fix typo

* Add circlci, remove .travis.yml. Fixes #1839.

* Fix circleci config

* Add slack notification

* Add circleci status

* Fix config.yml, we don't need separate truffle image and instances.

* Matches oz-sdk node version

* Seems node:10.13 doesn't work for CircleCI either

* Remove npm update in circleci

* CircleCI use package-lock.json as cache key and install only the lock version

* Add back travis.yml

* Rename job build to test

* CircleCI requires that job to be called build instead of test or build_and_test

* Fix the way to run jobs

* Fix CircleCI

* Change back to npm install

* Add workflow and split into tasks

* Add workspace

* Restore cache

* update readme circleci instructions

* make step name more accurate

* Imporvement: functions in SafeMath contract overloaded to accept custom error messages.

* CHANGELOG updated, custom error messages added to ERC20, ERC721 and ERC777 for subtraction related exceptions.

* SafeMath overloads for 'add' and 'mul' removed.

* Error messages modified.

* Update CHANGELOG.md

* added _safeTransferFrom function

* added safeMint functions

* added package-lock.json for consistency, don't know why it changes

* added initial suggestions/modifications

* change _safeTransferFrom to internal, reverted package-lock.json to original, and changed ERC721Pausable to override _transferFrom instead of transferFrom

* included tests for safeMint functions

* modified safeMint tests to be on ERC721Mock contract

* added safeMint to ERC721Mintable & respective test to ERC721MintBurn.behavior.js

* Rename package and repository name from docs and scripts

* undo root package rename

* add @openzeppelin/contracts as subpackage with release automation

* synchronize @openzeppelin/contracts version

* remove private field from package.json

* make file patterns absolute

* change wording of a comment

* use a saner version script

Add: Interface names should have a capital I prefix.

* add OwnableCautious with associated mock and tests

* extraneous comma removal and cleanup

* remove non-documentation changes from branch

Change URLs to openzeppelin.com

Update URLs and names to OpenZeppelin and OpenZeppelin Contracts

Update URL to openzeppelin.com

* update readme with new branding

* update readme text with new branding and links

* add newer link to api stability document

Squashed commit of the following:

commit fcf35eb806100de300bd9803ce3150dde1ecc424
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 17 17:16:04 2019 -0300

    remove all docsite dependency

commit eeaee9a9d43d70704f6ab17b5126ddbd52b93a50
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 17 17:15:23 2019 -0300

    update solidity-docgen

commit f021ff951829ea0c155186749819403c6b76e803
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 17 17:05:06 2019 -0300

    update docsite script for new setup

commit ff887699d381cfbbe3acf1f1c0de8e22b58480f3
Merge: c938aa1d 84f85a41
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 17 16:46:46 2019 -0300

    Merge branch 'master' into antora

commit c938aa1d9ed05ac83a34e2cebd8353f8331ad6d6
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jul 16 18:24:29 2019 -0300

    make component name shorter

commit 5bbd6931e02cbbd8864c82655ad0f390ceead5f3
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 20:16:17 2019 -0300

    add all info to docs templates

commit 39682c4515d7cf0f0368ed557f50d2709174208a
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 20:13:49 2019 -0300

    fix npm docsite script

commit 7ae46bd4a0437abf66150d54d05adf46e3de2cab
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 18:48:05 2019 -0300

    convert inline docs to asciidoc

commit cfdfd3dee4b4bf582fde22c8cb6e17a603d6e0c8
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 17:34:52 2019 -0300

    add missing contract names in readmes

commit 15b6a2f9bfb546cf1d3bf4f104278b118bf1b3f4
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 17:16:47 2019 -0300

    fix script path

commit 80d82b909f9460d1450d401f00b3f309da506b29
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 17:13:53 2019 -0300

    update version of solidity-docgen

commit a870b6c607b9c2d0012f8a60a4ed1a1c8b7e8ebd
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 17:03:53 2019 -0300

    add nav generation of api ref

commit 069cff4a25b83752650b54b86d85608c2f547e5e
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Wed Jul 10 16:32:14 2019 -0300

    initial migration to asciidoc and new docgen version

commit 55216eed0a6551da913c8d1da4b2a0d0d3faa1a8
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 20:39:35 2019 -0300

    add basic api doc example

commit 0cbe50ce2173b6d1d9a698329d91220f58822a53
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 19:31:31 2019 -0300

    add sidebars

commit 256fc942845307258ac9dc25aace48117fa10f79
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 15:22:38 2019 -0300

    add page titles

commit f4d0effa70e1fc0662729863e8ee72a8821bc458
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 15:19:41 2019 -0300

    add contracts index file

commit b73b06359979f7d933df7f2b283c50cb1c31b2a0
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 15:14:52 2019 -0300

    fix header levels

commit fb57d9b820f09a1b7c04eed1a205be0e45866cac
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 15:11:47 2019 -0300

    switch format to preferred asciidoctor format

commit 032181d8804137332c71534753929d080a31a71f
Author: Francisco Giordano <frangio.1@gmail.com>
Date:   Tue Jun 25 15:05:38 2019 -0300

    initialize antora component and convert docs to asciidoc

Bumps [lodash](https://github.com/lodash/lodash) from 4.17.11 to 4.17.14.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](https://github.com/lodash/lodash/compare/4.17.11...4.17.14)

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

Correct typo: 
2 * 0.5e18 = 10^18 = 1e18

Change reference to Tokens documentation
Fix typo `CROWDALE_ADDRESS` to `CROWDSALE_ADDRESS`

Resolve compilation errors in sample contracts:
* Change `address wallet` to `address payable wallet` in multiple sample contracts
* Change `ERC20 token` to `IERC20 token` in multiple sample contracts
* Reorder inheritance of crowdsales to prevent error: "Linearization of inheritance graph impossible" in multiple sample contracts
* Change `startTime` to constructor parameter `openingTime`

Bumps [lodash.merge](https://github.com/lodash/lodash) from 4.6.1 to 4.6.2.
- [Release notes](https://github.com/lodash/lodash/releases)
- [Commits](https://github.com/lodash/lodash/commits)

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

Fix typo

fixes #1814

* Using extcodehash instead of extcodesize for less gas

`extcodehash` uses less gas then `extcodesize`. You can tell which address is a contract by the hash (see EIP-1052).

* Fix

* Add explainer

* Update Address.sol

* add changelog entry

* changed exxpect to expect wherever applicable

* Merged with latest branch

* Updated merkleTree helper to latest master branch

* Made linting fixes

* Fix for test build

* updated for Coverage

* Updated Address.test.js

* Undo package-lock changes.

* Improved tokens guide, add ERC777.

* Fix typo.

* Add release schedule and api stability.

* Add erc20 supply guide.

* Revamp get started

* Add Solidity version to examples

* Update access control guide.

* Add small disclaimer to blog guides

* Update tokens guide.

* Update docs/access-control.md

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

* Update docs/access-control.md

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

* Update docs/access-control.md

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

* Apply suggestions from code review

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

* Apply suggestions from code review

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

* Documentation: Typos and add npm init -y to setup instructions (#1793)

* Fix typos in GameItem ERC721 sample contract

* Add npm init -y to create package.json

* Address review comments.

Fixing typo in comment line 9

* 20x performance for merkle tree lib

* add semicolon

* Update test/helpers/merkleTree.js

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

* Simplification and optimization of existing contracts #8888

* Simplification of SimpleToken

* This is the fixed Simplification

* My bad I'm playing around with this git stuff, should be correct now

* add missing parenthesis