Refactor to enable hooks to work per instance and accessing fun arg_types
Refactor to enable hooks to work per instance and accessing fun arg_types

The previous implementation had two undesirable side effects:
1.- a single wrapper was used for all the instances of the same class.
2.- argtypes and restype properties of ctypes function could not be
    easily accessed

This patch corrects these problems using a Wrapper class.

varses/awsch,LabPy/lantz,LabPy/lantz_qt,LabPy/lantz_qt,LabPy/lantz,LabPy/lantz_qt,varses/awsch,LabPy/lantz,LabPy/lantz