* Remove redundant require statements

Now that SafeMath uses require, the require statements are redundant. They were also previously inconsistent because they were only included in some functions, but not others

* Update ERC20.sol

* add improvement in simpletoken example #1458

* fix not calling decimals get function in initial supply

* signing prefix added

* Minor improvement

* Tests changed

* Successfully tested

* Minor improvements

* Minor improvements

* Revert "Dangling commas are now required. (#1359)"

This reverts commit a6889776.

* updates

* fixes #1404

* approve failing test

* suggested changes done

* ISafeERC20 removed

* conflict fixes

* fixes #1386

* Update SafeMath.test.js

* signing prefix added

* Minor improvement

* Tests changed

* Successfully tested

* Minor improvements

* Minor improvements

* Revert "Dangling commas are now required. (#1359)"

This reverts commit a6889776.

* updates

* fixes #1404

* approve failing test

* suggested changes done

* ISafeERC20 removed

* conflict fixes

* fixes #1456

* fix Add a comment to ERC721Enumerable #1465

* fix Add comments to ERC721Burnable #1464

This attack was reported in https://github.com/OpenZeppelin/openzeppelin-solidity/issues/877

* Made _clearApproval private, added clarifying comments in _addTokenTo and _removeTokenFrom.

* Added approval information.

* Deleted unnecessary import.

* Added back SafeMath.

* Removed another unnecessary import.

Now setting the finalized flag before doing finalization to prevent possbile reentrancy issues. (#1447)

* Added a small Crowdsale fallback gas warning.

* Fixed a couple typos.

* Made some internal crowdsale methods internal.

* Made all Crowdsale constructors internal.

* signing prefix added

* Minor improvement

* Tests changed

* Successfully tested

* Minor improvements

* Minor improvements

* Revert "Dangling commas are now required. (#1359)"

This reverts commit a6889776.

* updates

* fixes #1404

* approve failing test

* suggested changes done

* ISafeERC20 removed

* allowance methods in library

* Improved SafeERC20 tests.

* Fixed test coverage.

* Improved TokenVesting events.

* Added extra checks to TokenVesting.

* Renamed the events.

* Fixed linter error.

* Fixed a test that failed to cover a require.

* Renamed TokensRevoked to TokenVestingRevoked.

* Renamed file, added events and set _addPayee to private

* unwanted file

* adjusted test

* adjusted test

* PaymentReceived event added

* Added event testing.

* Fix static tests

* Added address of pauser/unpauser in events

* Added the account to the Pausable tests.

* Update contracts/ownership/Secondary.sol

* Update Secondary.sol

* Update Secondary.test.js

* Update Secondary.test.js

* Update Secondary.sol

* Made some inherit-only contracts internal.

* Added OwnableMock.

* Made some TokenVesting public functions private.

* Fixed linter error.

* Moved Escrows into an escrow subdirectory, improved docs.

* Fixed escrow mock.

* Fixed some more imports.

* added function to renounce ownership

* Make state variables private (#1411)