When the wrappers add custom methods like AddObserver() they should
ensure that the orginal method of the same name is not wrapped or
the override will not be successful (or worse, there will be duplicate
symbols and the wrappers won't even compile).

As a side-entry to this commit, I've also made "unsigned long" return
values as python ints unless they are too large, in which case they
are returned as python longs.