Add "cs" command

[aik099]

For single-class analysis the PHP_CodeSniffer is the best tool to use. However it can't do cross-class analysis.

Things to check:

1. no E_STRICT violations (ensure, that sub-class method signature is substr of all parent classes method signature)

[aik099]

Ideas from https://github.com/nette/updater/blob/master/src/Analyzer.php :

How to check

1. get class own methods (without extended ones)
2. use ReflectionMethod::getPrototype to get method from class (in class hierarchy) where this method is declared
3. compare with prototype
4. get interfaces, which this class implements
5. if method is found in any of interfaces (including interfaces, extended from other interfaces) then compare method with it's version from interface

What is considered a strict notice:

• extending a final method
• extended method returns value by reference, while original method isn't
• return type mismatch (php 7 only)
• extended method has more required parameters
• extended method parameter was turned into variadic or back
• extended method parameter was turned into passed by reference or back
• extended method parameter type was changed