osc: Add internal tracklist management

The track-buttons will now work on internal tracklists to provide the necessary flexibillity. Input is always proccessed based on the currently actiuve track ID in mpv to make sure everything always stays in sync.
The iAmAProgrammer-mode will soon be modified to entirely disable the internal playlists (and functions that build on them)
osc: iAmAProgrammer-mode will now disable OSC internal tracklists

This will also disable the display of ammount of tracks, disabling of track buttons if there are no tracks of that type, and the shift-click tracklisting.
osd: change symbol font name to "mpv-osd-symbols" to avoid confusion with osd-font option
osc: try to make Kovensky happy

some more variables for positioning and stuff