MacOS X compat

So now the python modules don't link against libpython but use "-undefined dynamic_lookup".

```
% otool -L _inference.so
_inference.so:
        /opt/local/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 7.17.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 169.3.0)
        /opt/local/lib/gcc47/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)
```
Awesome, let me just disable ICM and see how it goes.