MBS-5989: Ignore <span> for name-variation purposes

Artist and recording links where the visible text does not match the
entity name get a "name-variation" CSS class so that users may choose
to have them highlighted. However, the diffing code used in edit
display adds some <span> tags that trigger the "name-variation" marker
even where the user-visible text does match the entity name. This is
fixed by filtering any <span> tags from the display text before
comparing it to the entity name.
MBS-7721: Fix off-by-one when adding tracks

When switching, in the release editor, to a CD TOC with more tracks
than currently in the tracklist, the new tracks are initialized with a
position value that is off by one (too low), so that the first added
track has the same position as the previously last track.
MBS-5995: Show entity name in tooltip if different

If the text of an artist or recording link differs from the entity
name, show the latter in a tooltip, together with any extra
information that may already be scheduled for it (such as the artist
sortname).
Add some checks for medium edits

Upon initializing an add/edit medium edit, check the tracklist for
possible problems such as non-unique track IDs or track positions.
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-7852: Relationships should only be loaded where necessary
MBS-7851: Re-align voting radio buttons

The attribute "class" had been accidentally changed to "clpass" for
two voting radio buttons, which meant it was no longer recognized for
CSS styling, leading to misalignment of the buttons.
MBS-6088: Serialize edits_pending in rel. target

The edits_pending value for the target entity of a relationship was
not put into the JSON data for the release overview page; hence,
entities having pending edits weren't highlighted.
Remove unnecessary line in Controller::Role::Edit
Move direct load_subset call to Controller::Role::Load param
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