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

13.1rc1
Revert "demuxer ffmpeg, workaround for broken probing of flac format", unneeded for ffmpeg2.2/gotham-improved

This reverts commit b38ec398546e87679f94e829eb87ed5f71a05149.
Revert "VDPAU: improve error handling, Gotham"

This reverts commit 55030587d56f54a56655fd9ad7e419e4077b7e57, which conflicts with the ffmpeg2 variant.
[depends] move ffmpeg to unified deps
[configure] remove internal ffmpeg
remove ffmpeg from tree
ffmpeg: remove dll wrappers
add ffmpeg lock manager
todo: refactor to own file
ffmpeg: move callbacks into separate file
remove ffmpeg dlls from generated headers
not removing win32 as this might still be needed?
[rpi] setup-sdk.sh: allow overriding of buildroot and xbmc install paths
also don't require root if not needed
add ffmpeg makefile for rpi
[WIN32] download and compile ffmpeg from remote source.
[WIN32] make XBMC compile, build and run with the ffmpeg link libraries.
[WIN32] use ffmpeg version from tools\depends\target\ffmpeg\FFMPEG-VERSION
[WIN32] prepare mingw build files for jenkins.
[WIN32] removed old mingw build files.
ffmpeg: bump version to 2.2
[depends] add --with-platform=raspberry-pi switch