[release] version bump to 13.0 alpha2 as we start new merge window.
Add compilationartist property to AudioLibrary.GetArtists
Remove unused variable initialization
[rbp] Fix for audiotoggledigital on Pi.

Pi only has two audio output modes so the three way toggle gets stuck. This fix corresponds to Pi specific settings code:
https://github.com/xbmc/xbmc/blob/master/xbmc/settings/GUISettings.cpp#L458
[droid] remove unnecessary logging on touch input events
turn EVENT_RESULT enum values into flags
[win32] adjust touch gesture handling
input: implement touch input through mappable actions
input: re-organize touch input handling to make it more generic and move it into its own lib
touch: add touch gesture detectors for pinch/zoom, rotate and swipe
touch: make the touchscreen's DPI available to gesture detectors
CSlideShowPicture: add m_bCanMoveVertically
slideshow: use swipe left/right gestures instead of manual swipe detection based on pan gesture
[ios] - add unified gesture handler to ios xcode project
[ios] - use generic touch handler
[ios] - implement swipe support
[touch] add a mapping for 2 finger swipeleft (Back) as it was before on iOS because of lack of hw back button
Add support for limits to Files.GetDirectory

Also removes an unneeded loop.
Merge pull request #2366 from Tolriq/AddLimitsToFilesGetDirectory

jsonrpc: add support for limits to Files.GetDirectory
Merge pull request #2248 from Tolriq/compilationartist

jsonrpc: add compilationartist property to AudioLibrary.GetArtists