Added tests for correct handling of function argument type hints
Added (failing) tests for handling parent:: calls
Added resolving of parent::method calls to correct class

Changed class hierarchy storage in PHPDCD_Analyser from parent->children mapping to child->parent mapping, which parent handling easier and getClassDescendants also more efficient.
Don't mix up functions and methods with same name

Methods on objects of which type can not be inferred, should be registered as method call, not function call