upnp: ask if user wishes to stop playback on remote device on stop

This allow user to detach from a remote upnp player without
stopping playback.
upnp: split attach and play function in player

This avoids delay when attaching to stopped player.
upnp: reindent after previous commit
Merge pull request #4020 from elupus/upnpplayer

UPnP player disconnect/attach improvements
FIX: [droid] prevent the os from shutting us down if a touchpad device is added/removed
Merge pull request #4053 from koying/quickpr

FIX: [droid] prevent the os from shutting us down if a touchpad device i...
Strings: Update description and setting name for multi thread frame decoding
DVDVideoCodecFFmpeg: Disable hw acceleration when frame threading is enabled
Settings: Disable vdpau / vaapi / dxva2 / openmax if frame threading is selected