Beta Hybrid Citybus 8.2.1

I finally had time to update this! This update fixes a few internal things so that it works correctly on the latest version of the game.

In addition, there is now an Electric Air Compressor part that comes pre-installed on all of the Hybrid and Electric configurations! This makes these variants fully usable again since the pneumatic system changes in 0.32 and 0.33. The air compressor will automatically cycle on and off as needed whenever the bus is turned on to keep the air tank pressure high enough for the brakes, suspension, and doors to work correctly.