soundplugin: Remove workaround for quodlibet

QuodLibet's MPRIS plugin reports the correct mpris:length value at least since
version 2.4 (released 2012-03-18).
panel launchers: fix icon size during panel scale mode
cinnamon schema: provide a range max for panel height keys - this crashes
dconf-editor otherwise.
Merge pull request #3061 from rscholer/soundplugin_length

soundplugin: Remove workaround for quodlibet
menu applet: Remove visibility checks for button actors, ClutterActor
already optimizes out show/hide if there's nothing to do.
windowManager.js: When closing a minimized window, like from the window
list applet, don't briefly show the window before it gets destroyed.
windowManager.js: bit more cleanup regarding opacity
Update global.get_current_time()

https://git.gnome.org/browse/gnome-shell/commit/?id=5566aa45889956b51149a822ff5b9adbcb66ec29
theme-node: apply scale factor to border-image values
put single page xlet settings inside of a SectionBg
windowManager.js: Fix one more opacity problem
Merge pull request #3072 from JosephMcc/xlets1

put single page xlet settings inside of a SectionBg
Fix assert errors at beginning of cinnamon settings when trying to
launch to a specific page directly.
Add symbolic icons for actions
Merge pull request #3079 from RavetcoFX/a31

Add symbolic icons for actions
Fix new symbolic icons, change their category so they stay consistent with
the other icons
Add show-desktop toggle to hotcorners
Fix assertion when starting cinnamon-settings-users
cinnamon-settings user: fix accidentally adding a widget twice