Merge pull request #487 from avuton/master

widgets: Fix line endings, remove duplication, unused code paths, docbook
Fix new Artist tag to use setting broken due to missing "break" statement.
Sliding up panel is now draggable from everywhere and allows horizontal touches, much like Play Music's implementation
Merge 3rd party patch so that Sliding Up Panel allows to scroll our listview.

Also add credits to the about window
Restore small now playing previous button visibility
Tablet bugfixes
New icons, courtesy of the Android Asset Studio !
Shamelessly copying Google Play Music's tablet layout
Bugfixes and light color tweaks
1.07 Beta 4