Check PHPDoc and typehints declaration

[VasekPurchart]

• check for missing property types in PHPDoc @var
• check for missing typehints in case they can be declared
• check for missing @return and/or native return typehint in case the method body contains return with a value
• check for useless doc comments
• forces to specify what's in traversable types like array, iterable and \Traversable