gui: add Player.Title to replace VideoPlayer.Title and MusicPlayer.Title
confluence: use Player.Title instead of (Music/Video)Player.Title

This label is generic and support non video/audio players as well
gui: allow reporting of playback time for a non av player

Shows info for a upnp remote player
gui: allow progress tracking for non video/audio players
gui: don't allow context menu recursion

Could happen if a button was directly mapped to a context menu.
paplayer: bring OnPlaybackStarted/Stopped in line with dvdplayer
sys: only reset forced player on playback stopped

This will allow a forced player to continue advancing in a playlist.
sys: add methods for dynamic player addition/removal to PlayerCoreFactory
Platinum: don't disregard PLT_MediaObjects only for lacking resources
upnp: add support for controlling external player
sys: add action "switchplayer" that allows switch of forced player

This allow moving a playing item to a another player (remote upnp
for example)

It's hooked up to "t" on keyboard currently.
gui: make sure we leave fullscreen if we start a player without media
upnp: issue Stop before SetAVTransportURI to make sure it's stopped

Renderers should reject this call if not stopped according to
DLNA
upnp: do a full LoadItem from thumb loaders instead of FillLibraryArt
upnp: factor out code that build a CFileItem from a PLT_MediaObject
upnp: use standard methods to build CFileItem in renderer
Platinum: add SetNextAVTransportURI support to media renderer base
upnp: renderer support for SetNextAVTransportURI