mplayer: don't make restored options from quit_watch_later per-file local

Consider:

    mpv file1.mkv file2.mkv

and file1.mkv is restored from an earlier session when quit_watch_later
was used. Then all restored options were reset when file2.mkv is played,
even if the user changed them during playback. This affects for example
the fullscreen setting.

Make it so that after finishing a resumed file, the previously restored
settings are not reset again. (Which means only resuming will forcefully
overwrite the settings.)
vo_vdpau: fix screenshots if panscan is used

When panscan was used, i.e. the video is cropped to make the video fill
the screen if video and screen aspects don't match, screenshots
contained only the visible region of the source video, stretched to
original video size.