Py3k compatible

Pyhull is now completely Py3k compatible.

Minor update for precision

1. Use the proper way to preserve float precision using repr.

Minor bug fix release

1. More precision fixes and bad code naming fixes.
   (Reported by Konrad Schneider).

Bug fix for precision loss

1. Fix the precision loss in conversion from floats to string in qhull_cmd
   (Reported by Konrad Schneider).