This commit also includes:
- whitespace / code formatting fixes
- slight syntax related changes: except <exception_name>, e -> except <exception_name> as e
- 3 pointless instructions instances have been rewritten [sorted] (spotted by semi-automatic check)
The unrelated changes shouldn't have any real impact on whipper's behaviour.
- output path no longer has fallbacks
- refactor accuraterip cache
- use requests to download accuraterip entries
- add tests for accuraterip functionality
- remove gobject support from accuraterip-checksum calculation
- default track template now includes extension
- begin to remove support for continuing rip
- begin to use print instead of sys.stdout.write() throughout