Replace temporary encounter mesh with encounter meshes

[jelster]

Currently, all encounters are being represented as simple Sphere meshes. In order to be able to present a dynamic, compelling gameplay experience, the game needs to be able to use different meshes and potentially different logic for the encounters during the driving phase.

Example: Space-Porta-Potty Pickups might have an animated PS that makes the pickup flash for attention

Space-traffic jams might have dozens of vehicles clogging the route, each appearing to move, bob, float, etc