Fix identity monodromy element handling.

monodromy() incorrectly handled identity elements. monodromy()
now only returns non-trivial element along with their branch
points. This should improve homology performance, too.
Add homology plotting routine.
Homfix checkpoint.
Fix homology's linear combination algorithm.

Thorough examination of the homology algorithm was done
for examples f3 and f4. No errors were thown for the
other examples. Since new data is kept track of in the
homology graph the c-cycle construction algorithms still
need to be updated.