Turns out Neil didn't intend for *all* of his gen-branch work to get

Turns out Neil didn't intend for *all* of his gen-branch work to get
committed.

tokenize.py:  I like these changes, and have tested them extensively
without even realizing it, so I just updated the docstring and the docs.

tabnanny.py:  Also liked this, but did a little code fiddling.  I should
really rewrite this to *exploit* generators, but that's near the bottom
of my effort/benefit scale so doubt I'll get to it anytime soon (it
would be most useful as a non-trivial example of ideal use of generators;
but test_generators.py has already grown plenty of food-for-thought
examples).

inspect.py:  I'm sure Ping intended for this to continue running even
under 1.5.2, so I reverted this to the last pre-gen-branch version.  The
"bugfix" I checked in in-between was actually repairing a bug *introduced*
by the conversion to generators, so it's OK that the reverted version
doesn't reflect that checkin.