[Python-mode] making stack traces clickable in gud.el pdb output.

[Jeff Bauer]

> "clickable"?  Is that like using that mouse thing?  To
> paraphrase a wise man, "There's no clicking in Emacs!" :)

But the track ball scroll wheel is AWESOME.

I've never tried running pdb from an emacs shell.  Thanks
for the tip!

Jeff Bauer
Rubicon, Inc.