Shade skin - cover art support - set minimum size to 100x100
LateNight skin - cover art support - uncomment show/hide control
the show/hide control already works for LateNight
Deere skin - cover art support - add show/hide control
Merge pull request #383 from cardinot/cover_skins

some fixes for skins containing the cover art widget
dlgtrackinfo - location field - fixing bug with background color
Fix case where BaseTrackCache wasn't receiving dirty notifications if a
track begins life dirty.

Fixes Bug #1392917.
Only preserve legacy key text as user data if it is non-empty.

This was setting most tracks to dirty unnecessarily.
Move new end-of-track warning slider from the debug section up next to the other existing slider. Added a tooltip, changed the label as discussed in #352
Update translation template. Found 1826 source text(s) (14 new and 1812 already existing).
Merge pull request #386 from cardinot/bug_dlgtrackinfo

[#1392927]dlgtrackinfo - location field - fixing bug with background color
Contributor updates.

* Move Mark Hills to "Special Thanks".
* Remove duplicate "Alex Barker".
* Add some missing contributors from the 1.12.0 milestone page:
 - Kevin Wern
 - Varun Jewalikar
 - Keith Salisbury
 - Irina Grosu
 - Callum Styan
 - Rahul Behl
* Move Dennis Wallace to this-release contributors.
Update credits page.

* Move people who haven't contributed significantly to 1.12 to the past
  developers/contributors list.