segfaults in ipython

I would consider this a python bug, and I just added a

    > quick fix for me. Changed line 511 in to say
    > if self.Pprint and hasattr(arg, '__repr__'): instead of
    > if self.Pprint:

    > You probably don't want to add this for everything, but
    > would it be possible to override the display method of
    > the CachedOutput when the pylab option is specified?
    > Further, you could only do this for python v.2.4.

I'll see if I can add repr to all the pycxx mpl classes. Perhaps this
is the cause of the issubclass segfault as well, which would be a
great bonus.