Adding array comparison methods

Allows comparison of two arrays (just values, just keys or keys and values) while ignoring the item order. You can use callbacks, too.
Code styling
Code styling 2

The other changes are kind of acceptable, this actually makes the code harder to read and less structurized.
Bug fixing

... and is a possible source of mistakes
Adding wcf\system\Callback type hint
Type hint null
Merge pull request #1155 from PhrozenByte/enhancement/ArrayCompare

Adding array comparison methods