OH MY GOD I'M FINALLY DONE.

* Added exclusions module with a fully implemented ExclusionsDB that can pull
  from multiple sources for different sites.
* Moved CopyvioCheckResult to its own module, to be imported by __init__.
* Some other related changes.

Make trout command change target yourself to himself

Obviously this can and should be improved significantly later, but it seems
good enough for now.

Also implementing MWParserFromHell, plus some cleanup.