Added item identity providers and converters
Updating tvdb providers to use item identities
Sort identities by provider order
added IsTextSubtitleStream
chapter downloading fixes
set language on chapter search
update ffmpeg
fix ffmpeg date
Merge pull request #811 from thogil/item_identity_providers_2

Item identity providers
Fix for VTT writer

Doesn't support <br/> tags
Merge pull request #842 from timhobbs/upstream-master

Fix for VTT writer
remove <br/> from parsed subtitles
Merge branch 'master' of https://github.com/MediaBrowser/MediaBrowser

Conflicts:
	MediaBrowser.MediaEncoding/Subtitles/VttWriter.cs
fixes #843 - Update Dlna to respect user audio/subtitle language settings