translate code for Python 3.x compat

I merely used `2to3` and checked it for sanity. The only bit you might have a problem with is the line 10 of `util/gensource.py` which translated from xrange to range. Since range will build the full list (on 2.X), xrange does make more sense. Then again, 10000 entries will not exhaust anyone's memory these days.

I installed my updates and ran `make test` for python 2.7 and 3.3. They both had identical outputs to your pypi version. (Test reservoir failed across the board.)