target broadcasting and numpy array support for generics

adresses #468 (closed)

• added target broadcasting for generics
• added support for numpy arrays as generic function return when those match the target frame in shape

-> i noted in the changelog.md there was already an entry stating broadcasting support was added already for flagGeneric: i didnt get into that, but a simple flagGeneric('v', func=lambda x: True) threw an exception complaining return type wasnt a series -> so didnt really work for the use case