#1 classmethod support

[ill-665]

Python knows two kinds of static methods.
1. the classical static methods defined like:
def foo ():
....
foo = staticmethod(foo)

2. class methods with a reference to the class object as first parameter looking like:
def bar (cls)
...
bar = classmethod (bar)

PyUML should support the different kinds and create a classmethod call, if a static method has "cls" as first parameter