BUGFIX, DOC: Tamed Epytext throughout the land.

No code was touched.  Only docstrings.

To the extent possible, this commit only concerns minimal corrections
necessary to build API documentation correctly.  The style and content
will be improved in later commits.

The bugs that remain are:

- NetworkX is mysteriously imported and parses incorrectly.
- arguments that have @param ... clauses in functions that use *args
- "Redefinition of type for iterable" warning given for mathset.PowerSet
- indentation troubles in polytope/esp.py.
DOC: Make links and improve style throughout docstrings
Merge pull request #63 from slivingston/doc

Improve documentation