no need to manually set the display resolution anymore
CDisplaySettings: improve screen options filler to determine the current screen
settings: make sure videoscreen.screen/resolution change if videoscreen.screenmode is changed
settings: add OnSettingPropertyChanged callback to ISettingCallback
settings: add IsEnabled() to CSetting
settings: move dependency logic from CGUIWindowSettingsCategory to CSettingsManager
CDisplaySettings: don't show a prompt when switching from/to windowed mode
remove unused methods from CSettings
vaapi: don't unmap non-existing buffer

Some h264's can end up calling ff_vaapi_render_picture after a seek
with no buffer allocated and vaUnmapBuffer will assert on a invalid
buffer.
ffmpeg: add patch file for vaapi fix
ffmpeg: fixup compile error in patch
[AirPlay] - added missing ifdef checks for HAS_AIRPLAY and HAS_AIRTUNES
[language] - fix swedish short date format - thx to blittan
Merge pull request #2738 from Montellese/fix_videoscreen_settings

settings: move dependency handling into CSettingsManager and fix videoscreen settings
settings: fix fallback of language region filler
build: fix Android build, probably others
droid: fix crash on startup on some devices
settings: fix dependency defintion of videoscreen.screen
[AirPlay] - fix missing ifdef guards for airtunes/airplay on server stop
[AirPlay] - removed some unneeded ifdef guards