Add a mark as watched/unwatched option to longpress dialogue

[todorus]

Both the Movies and Shows don't have an option to manually set them as watched/unwatched. I would really be able to do so for my own overview

[tousdan]

This is something that has been annoying me for a while. My only control over my xbmc machine is through a remote and ssh and I recently imported my library. Marking shows as watched or seasons instead of being able to do it only on a per episode basis would make it at least more bearable.