MBS-967: Support for hidden pre-gap tracks
Make resetTrackNumbers respect pregaps
Tweak wording of pregap option
Add support for virtual element containers to the loop bindingHandler
MBS-7784: Support for data tracks in tracklists
Return data tracks in /ws/2
Clarify comment
Make hasInvalidFormat take data tracks into account
Fix binding context of loop-binding descendants
Make sure track parser can't introduce non-contiguous data tracks
Add missing data track icons to the edit medium template
Remove no-longer-necessary div
Make tocChanged take the pregap into account
Merge branch 'schema-change-2014-q4' into mbs-967

Conflicts:
	admin/sql/updates/schema-change/21.standalone.sql
	lib/MusicBrainz/Server/Data/Track.pm
	root/cdtoc/set_durations.tt
	root/release/edit/tracklist.tt
	root/release/index.tt
	upgrade.json
Merge scripts so that functions are added to slaves
Move medium_index requirements into SQL clause, remove unneeded return
Move data track icon into CSS data-uri
Merge remote-tracking branch 'bitmap/mbs-967' into schema-change-2014-q4

* bitmap/mbs-967:
  Move data track icon into CSS data-uri
  Move medium_index requirements into SQL clause, remove unneeded return
  Merge scripts so that functions are added to slaves
  Make tocChanged take the pregap into account
  Remove no-longer-necessary div
  Add missing data track icons to the edit medium template
  Make sure track parser can't introduce non-contiguous data tracks
  Fix binding context of loop-binding descendants
  Make hasInvalidFormat take data tracks into account
  Clarify comment
  Return data tracks in /ws/2
  MBS-7784: Support for data tracks in tracklists
  Add support for virtual element containers to the loop bindingHandler
  Tweak wording of pregap option
  Make resetTrackNumbers respect pregaps
  MBS-967: Support for hidden pre-gap tracks