[rendercapture] Fix passthrough rendercapture interface

The RenderCapture function doesn't behave correctly for passthough video renderers,
and in fact segfaults on Pi when setting a bookmark.

There is no need to do a glReadPixels to get a video snapshot in the passthrough case,
so provide a shortcut.
[rbp] Support grabbing just the video layer through rendercapture

As the bookmark snapshot doesn't want the OSD (and neither does boblight)
allow video, or video + GUI to be selectable.

While we're there, making the GPU do the red/blue swap and stride packing saves some cpu.

Requires updated firmware
[addons] add Gotham repositoy
[LangCodeExpander] Add method CompareLangCodes(const CStdString& code1, const CStdString& code2).
Its purpose is to determine if two languages given as ISO 639-1, ISO 639-2/T, or ISO 639-2/B codes represent the same language.
[LangCodeExpander] Add method CompareFullLangNames(const CStdString& lang1, const CStdString& lang2).
Its purpose is to determine if two english language names represent the same language.
For example "Abkhaz" and "Abkhazian" represent the same language.
[DVD/OMXPlayer] Fix auto-selection of audio and subtitle streams by using a generic language compare method.
XBMC's audio and subtitle language is stored as an ISO 639-2 T code, but a video's metadata could also store it as an ISO 639-2 B code which could differ from the T variant.
ffmpeg backport: h264: do not discard NAL_SEI when skipping frames
add ffmpeg patchfile for backport ab433b250ef3eb74a09be37612e806328451be65
VAAPI: Check supported libva-driver-intel to see if 4K decoding is possible
Merge pull request #3224 from fritsch/vaapi-check-4k

VAAPI: Check supported libva-driver-intel to see if 4K decoding can be done (thx @ elupus)
Merge pull request #3210 from popcornmix/passthrough_capture

[rendercapture] Fix passthrough rendercapture interface
[DVD/OMXPlayer] Always use the first entry of a language code in the mixed ISO 639-2 T/B code table.
Merge pull request #2839 from ace20022/fix_lang_select

 [DVD/OMXPlayer] Fix auto-selection of audio and subtitle streams.
Merge pull request #3208 from FernetMenta/audiostream

dvdplayer: fix accurate seek
[WIN32] cosmetics: removed some XP only code.
[gui] bump gui version but keep backwards compatible with previous version
[skin] set Confluence GUI dependency to 5.0.0 and do version bump
[skin] Updated Touched skin
Merge pull request #3213 from MartijnKaijser/gui_bump

[gui] bump gui version but keep backwards compatible with previous versi...
Merge pull request #3216 from MartijnKaijser/gotham_repo

[addons] add Gotham repositoy