Drop Python 3.7, fix genre shenanigans, parse 'with' and 'w/'

[snejus]

Removed

• Dropped support for python 3.7.

Fixed

• (Album metadata retrieval fails when no keywords(/genres) exist #52) genre: do not fail parsing a release without any keywords, for example https://amniote-editions.bandcamp.com/album/ae-mj-0011-the-collective-capsule-vol-1
• (Confusion about how beetcamp grabs genres #54) Ensure that our genre matching rules also apply to genres delimited by a dash, not only space.

Updated

• album:

  • handle some edge cases when string EP or LP is followed with data relevant to the album
  • do not remove artist or label when it is preceded by x or followed by characters ', _ and &, or words EP, LP and deluxe
  • handle apostrophes more reliably
  • Do not remove VA or V/A from the beginning when followed by a word or a number

• album / title:

  • Remove Various - from album and track names
  • Handle this album sent to us by the devil himself

• catalognum:

  • allow catalogue numbers like Dystopian LP01
  • parse a range of catalogue numbers when it is present, for example TFT013SR - TFT-016SR

• comments: use value None when there are no comments. In contrast to returning an empty string, this way during beets import the previous comment on the track will be kept if the Bandcamp release does not have a description.

• label: label is now correctly obtained for single releases when it is available.

• title:

  • consider with and w/ as markers for collaborating artists
  • remove bonus - - Artist - Title (bonus - something) -> Artist - Title (something)

[coveralls]

Pull Request Test Coverage Report for Build 8868630102

Details

• 340 of 353 (96.32%) changed or added relevant lines in 7 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.7%) to 90.85%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
beetsplug/bandcamp/album.py	52	54	96.3%
beetsplug/bandcamp/track_names.py	81	83	97.59%
beetsplug/bandcamp/tracks.py	69	71	97.18%
beetsplug/bandcamp/init.py	42	45	93.33%
beetsplug/bandcamp/helpers.py	18	22	81.82%

Totals
Change from base Build 5807104016:	2.7%
Covered Lines:	1012
Relevant Lines:	1111

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💛 - Coveralls