[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.
FIX: [droid] add additional droid keyboard code -> XBMC keyboard code mappings
FIX: [droid] don't forward unknown keys
ffmpeg backport: h264: do not discard NAL_SEI when skipping frames
add ffmpeg patchfile for backport ab433b250ef3eb74a09be37612e806328451be65
CPythonInvoker: fix log message format (thanks vdrfan)
Merge pull request #3218 from koying/fixdroidkeyboard

Various droid keyboard fixes
dxva: revert limit of video resolution

Seems most cards gracefully fail, and some card do support larger rez so allow it.
bluray: make sure root has no trailing slash

fixes Ticket #14579
bluray: make sure bluray play selection is shown from library
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.