* Add the solidity linter command to the PR template

The PR template states that a contributor should run the
Solidity/JS linters before submission. However, it only states the
command for the JS linter.

This commit adds the Solidity linter command explicitly.

* Use past tense in the list of prerequisites

Fix SafeERC20.safeApprove bug

(cherry picked from commit 3111291b)

Fix SafeERC20.safeApprove bug

(cherry picked from commit 3111291b)

Added PR links for 2.2.0 changelog entries.

Fix SafeERC20.safeApprove bug

Use canonical EIP reference format

Update to preferred citation formation for ERC-721

Add a link to the minime token

Fix typo: snapshoted

* ✏️ Refactor code & Refork OZ Repo

* Refactor ERC20Snapshot to use on-demand snapshots.

* Add ERC20Snapshot changelog entry.

* Move ERC20Snapshot to drafts.

* Improve changelog entry.

* Make snapshot tests clearer.

* Refactor ERC20Snapshots to use Counters.

* Refactor snapshot arrays into a struct.

* Remove .DS_Store files.

* Delete yarn.lock

* Fix linter error.

* simplify gitignore entry

* Add _setTokenURI internal.

* Rename TokenMetadata to ERC20Metadata.

* Add changelog entry for ERC20Metadata.

* Fix linter error.

* Add breaking change changelog notice.

* Updated code style to no more than120 characters per line.

* Unify code comments style with Doxygen-style tags.

* Add back solidity-coverage (using fork).

* Pin fork version.

* Improve SafeMath test coverage.

* Fix linter error.

* Split testCommutative into something more sane.

* Refactor Counter to support increment and decrement.

* Move Counter out of drafts.

* Refactor ERC721 to use Counter.

* Rollback Counter returning the current value in increment and decrement.

* Update test/drafts/Counter.test.js

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

* Improve Counter documentation.

* Move Counter.test to utils.

* Move back Counter to drafts.

* Add ERC20._approve.

* Add ERC20._approve tests.

* Fix linter error.

* Require owner in _approve to be non-zero.