Added description extractor functionality to the name checker as an

experimental service.

describe.py:
- Added an `unknown' type to the possible types of raw variants.
- Disabled the experimental LCSMatrix() code.



git-svn-id: https://humgenprojects.lumc.nl/svn/mutalyzer/trunk@596 eb6bd6ab-9ccd-42b9-aceb-e2899b4a52f1