Removed some black "flashing" that should have been invisible:

• between track guide teeth on various tracked vehicles
  
• around the muffler on trucks

The IS-2 treads' guide teeth were implemented up-side down, so I switched the treads out for the ISU-152's. The guide teeth look different, but photos and drawings show both types, and they are more consistent with the track parts mounted on the front of the vehicle.

Initial release.