Defined more function prototypes in ForthonObject
Updated to use correct numpy API for version 1.7
One more fix to numpy version 1.7 API
Cleanup of Forthon.h

Added comments and removed old code
Minor fix in Forthon.h for backwards compatibility
Minor fix in callpythonfunc for errormessage

Makes sure that errormessage is allocated before using it.
Now compatible with numpy API version 1.8