Added the Extrude functionality code, implemented the extruding code. The functionality doesn't work because had some problem:
if I read the currently selected object: OCAIS_InteractiveObject selectedInteractive = context.Current();
and try to get the underlying shape of the interactive object: OCAIS_Shape shape = selectedInteractive as OCAIS_Shape;
the cast fails even if the OCAIS_Shape class is derived from the OCAIS_InteractiveObject class. Need to investigate further how this cast works at the internal native handle and maybe also implement a DownCast method (or some equivalent) that exists at the OpenCascade header level.
Started adding on Sourceforge bugs at the Wrapper category.