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

saqc/funcs/generic.py

@@ -251,7 +251,10 @@ class GenericMixin:
         dfilter = kwargs.get("dfilter", BAD)
 
         dchunk, fchunk = self._data[fields].copy(), self._flags[fields].copy()
+        trg_idx = dchunk[dchunk.columns[0]].index
         result = _execGeneric(fchunk, dchunk, func, dfilter=dfilter)
+        result = _inferBroadcast(result, (len(trg_idx), len(targets)))
+        result = _inferDF(result, cols=targets, index=trg_idx)
         result = _castResult(result)
 
         if len(result.columns) > 1 and len(targets) != len(result.columns):