* Add IntelliJ IDE config to .gitignore

* Fix variable name in ERC20 function comments

* Fix typos in Arrays function comment

* Fix typos in ownership test names

* Fix typo in Pausable test name

* Fix grammar in Ownable function comment

* Fix grammar in Crowdsale contract comment

* Fix typo in Counters contract comment

* Fix typo in ERC721Enumerable comment

* Fix typo in ERC721PausedToken test name

* Fix typo in Crowdsale function comment

* Fix typo in IncreasingPriceCrowdsale function comment

* Fix grammar in IncreasingPriceCrowdsale test name

* Fix typo in AllowanceCrowdsale test name

* Fix typo in RefundEscrow function comment

* Fix typo in ERC20Migrator contract comment

* Fix typos in SignatureBouncer comments

* Fix typo in SignedSafeMath test name

* Fix typo in TokenVesting contract comment

* Move Ownable comment from @notice section to @dev

The Ownable contract has a comment explaining that renouncing
ownership will prevent execution of functions with the onlyOwner
modifier.

This commit moves that comment to the @dev section and replaces it
with a description suitable for a generic user.

* Clarify purpose of ERC20 transfer function

* Clarify registration of ERC721Enumerable interface

* Clarify purpose of AllowanceCrowdsale test

* Increase specificity of inheritance comments

FinalizableCrowdsale and RefundableCrowsale both have comments
indicating that they are extensions of the Crowdsale contract.

This commit refines those comments to the most immediate ancestor
( TimedCrowdsale and RefundableCrowdsale respectively )

* Remove unused parameter in PaymentSplitter test

* Rename parameter in SignatureBouncer functions

The SignatureBouncer contract has modifiers to validate the
message sender is authorised to perform an action. They pass
msg.sender to internal functions as the variable `account`, but
the function comments refer to the variable as `sender`

This commit changes the variable name to `sender`

* Clarify comments in SignatureBouncer functions

The SignatureBouncer has comments that use the description
`sender` to refer to the variable `account`.

This commit updates the comments for consistency.

Maintainer Note: this reverts changes in the previous commit,
which renamed the variable `account` instead.