Remove DiscNumberStyle functionality from guess case

It's been irrelevant since 2011.

Also removes other small, unused functions/variables.
Factor out common code from guesFoo functions
Simplify loop into a single line
Use common functions for alias sort name guessing
Add comment explaining use of work handler for series
MBS-7860: Internal server error when you pass /ws/js/release a non-existent MBID
Display a message in the release editor if the release fails to load
Remove trailing comma
MBS-7861: Exception using guess case on a medium with empty tracks
Merge remote-tracking branch 'bitmap/guess-case-unused-code' into beta

* bitmap/guess-case-unused-code:
  Add comment explaining use of work handler for series
  Use common functions for alias sort name guessing
  Simplify loop into a single line
  Factor out common code from guesFoo functions
  Remove DiscNumberStyle functionality from guess case
Merge remote-tracking branch 'bitmap/mbs-7861' into beta

* bitmap/mbs-7861:
  MBS-7861: Exception using guess case on a medium with empty tracks
Merge remote-tracking branch 'bitmap/mbs-7860' into beta

* bitmap/mbs-7860:
  Remove trailing comma
  Display a message in the release editor if the release fails to load
  MBS-7860: Internal server error when you pass /ws/js/release a non-existent MBID