Beta ETK800 Hybrid 8.1.0

I've made lots of improvements to the handling and performance of the hybrid system and fixed several bugs/nuances found by community members. This update to the ETK800 is accompanied by the same updates to the Citybus Hybrid!

Bugs fixed:
- Now works properly with cruise control app
- Vehicles with things such as daytime running lights (anything dependent on electrics.values.running) now work correctly even when the engine is off.
- Driving in reverse now drains battery instead of charging it (most likely only affected Citybus)
- Improve smoothness of engine starting/engaging while the vehicle is moving (overrev is far less likely)
- Vehicles are now more powerful when battery is extremely low (but the battery doesn't charge up as fast at high throttle)
- Regenerative brakes are more stable (no longer cause insane wheelspin for no apparent reason)