Update gitignore to exclude __pycache__
Run reindent to change tabs to spaces
Add disctitle feature

If the disc has a title create an according flac tag on all tracks on
that disc.  This is mostly interesting for multi-disc albums where each
disc has its own title (e.g. Devin Townsend Project - Z² has 3 discs:
Sky Blue, Dark Matters, Dark Matters Raw).