Reduce assets size

[Nomagno]

See kimden#21

[kimden]

I am ready to contribute to it. Please assign me.

[Nomagno]

While the design is pretty hardcoded, track_overlay_database.xml allows to add collectibles to any track without having to package it, which accounts for 90-95% of the needs of TME. Many tracks could be simply removed from the packaging now.