I recently screwed up some of the swig wrappers in trying to hunt down
a memory leak, so if you get segfaults with recent mpl builds, it's my
fault. I think I've fixed the problem, so if you encounter errors,
make sure you are using revision 2581 or later and do a clean rebuild
if necessary by rm -rf ing the build subdir.
Let me know if you see any strangeness...