This patch removes all PyMalloc_* symbols from the
source.  obmalloc now implements PyObject_{Malloc, 
Realloc, Free}.  PyObject_{New,NewVar} allocate using
pymalloc.

I also changed PyObject_Del and PyObject_GC_Del
so that they be used as function designators.  Is
changing the signature of PyObject_Del going to cause
any problems?  I had to add some extra typecasts when
assigning to tp_free.

Please review and assign back to me.

The next phase would be to cleanup the memory API
usage.  Do we want to replace all PyObject_Del calls
with PyObject_Free?  PyObject_Del seems to match better
with PyObject_GC_Del.

Oh yes, we also need to change PyMem_{Free, Del, ...} to
use pymalloc's free.