todo, easy
- get rid of compiler warnings
- make numpy optional
- need to figure out what to do with interactive output

later
- OUTPUT support
- use swig to create dependencies (-MM)

hacks
- cleanup does not work in pyton2.
- clone (when implemented in python) must keep a local reference, to trick garbage collector

bugs
- takes ages to compile
- error messages in loadpy...
- swig generated code is hard to test
