[release] version bump to 13.1 rc1
Merge pull request #4742 from MartijnKaijser/13.1rc1

13.1rc1
[library.xbmc.libretro] Fix crash when no settings are defined
Game API: Remove SetPixelFormat() callback
RetroPlayer: Remove SetPixelFormat()
library.xbmc.libretro: Remove SetPixelFormat() callback
Sync Xcode project
Merge remote-tracking branch 'xbmc/Gotham' into Gotham