Beta Hybrid Citybus 8.1.0

This is another pretty major update. I have studied the efficiency of the system a lot since 4.0, and have managed to greatly improve the fuel efficiency of both the etk800 and the citybus. Many thanks to @default0.0player for their help with engine efficiency curves and tips on how I could improve usage of the engine!

In addition to that:

• Brand new sounds! The inverter and motor sounds have been redesigned, and the air conditioning/compressor sound has been tweaked to be less obnoxious.
• Vehicle can now be turned off and on just like the non-hybrid cars in the game. On the bus, the engine will attempt to start as soon as the power is on, and must start successfully at least once before the vehicle can be driven.
  • You can start the vehicle up straight into EV mode by holding the binding for "Toggle EV Mode" while starting the vehicle, assuming the battery is charged enough. This overrides the last part of the previous bullet point.
  • If the vehicle is started with an extremely low hybrid battery (and has enough left to start the engine...) it will be disabled and locked in Park until the battery has charged up enough to drive.
  • If the vehicle is started and the hybrid battery cannot start the engine, the bus will try and use the DC starter motor instead. If this succeeds, the previous bullet point still applies. If it fails, the vehicle will not be driveable (duh).
• Engine startup while driving is smoother and faster, so sudden acceleration in EV mode which results in the engine being demanded on will have a quicker response time.
• Major improvements to regenerative braking
  • Brake pedal in D should feel almost exactly like driving a non-hybrid vehicle, and transition to friction braking at low speeds is smoother
  • Friction brakes are far less likely to engage at higher speeds as long as regenerative brakes can provide all the demanded braking torque
  • Once friction brakes do engage, unpropulsed wheels will engage before propulsed wheels to balance out braking force
  • ABS no longer disables regen braking, but a wheel having a speed that's a certain amount different from the rest will
  • Brake pedal in L feels more natural, especially at low speeds when regen brakes start to fade. You'll notice you have to press it much less aggressively to get hard braking in L.
  • Regenerative braking can bring the bus down to a much lower speed than before. It should be easier to maximize regen if you get a good feel for the brakes and use L when possible.
• eCVT transaxle is much better at balancing engine power. When the battery is in its "happy range" (no excess of power, and not starved of power), the total power in/out of the battery will be very close to zero except when moving the accelerator pedal or when flooring it. This helps keep the battery charged better while the engine is on so that it can be more useful when the engine is off.
  • It's also much easier to get the engine RPM down if the battery's decently charged. As long as it's above 35%-ish, the RPM should drop to near idle when cruising on flat ground, while still maintaining vehicle speed.
• Transition between eCVT modes (low-speed and high-speed modes) is almost unnoticeable now, unless you've somehow gotten the battery into extremely low levels (less than 0 on the UI app).