Beta Hybrid Citybus 8.1.0

This update adds rudimentary hybrid battery simulation to the bus. Light acceleration and gentle braking will utilize the hybrid battery best, taking some of the load off of the engine, which reduces fuel consumption and noise. Heavy acceleration or long uphill climbs will drain the battery faster and require the engine to work harder. Likewise, heavy braking with the brake pedal (instead of regenerative braking) will waste energy that could otherwise recharge the battery.

The battery charge level is not currently visible anywhere, but I'm looking into ways to display it in a future update.