Cleaned up precalc.py to make it (mostly) PEP4 compliant. There are a few lines that I don't understand well enough to dare touch, and a couple of PEP4 rules that I chose to ignore.
Fixed import of parse80 (to work on more computers)
Deleted orbit_cheby.py, since it is redundant now that there is a separate repository. (I forgot to put this in a separate commit, apparently, sorry).