Ignore .pyc, added evalHMM, some debugging

Fix bug where backtrace[0] was being included in testHMM output; as it
contains tag for dummy start, this needed to be excluded from final
tagged corpus.

As this and other bugs were fixed, removed some debugging output.

Added evalHMM.py; just a bare file atm. Will tell me how inaccurate my
output is compared to a reference file.

TODO: Complete evalHMM.py
TODO: Fix several inaccuracies. I'm rethinking how I use log
probabilities, and I should exclude the choice of dummy tags when
assigned a most likely tag. Smoothing should also be added.