Add move mode, shuffle, mpv config env, and option for playlist_view_toggle bind

[willswats]

• Move mode enables you to move the selected item in the playlist, by default it is toggled with "m"
• Shuffle, shuffles the playlist and moves the playing item to the start, by default it is "s"
• Mpv config env :/dir%mpvconf% to use the mpv config directory with thumbs_dir without writing out the full path
• Option for playlist_view_toggle bind so that it can be set inside playlistview.conf