Added engine weight to remaining vehicles.

Added Venom and Super Venom AI to Derby events.
Added Class B/C/D AI to Rocket RX.
Added Rocket RX AI to Derby events.

Reworked gearbox preset's gearing of nearly all V8 vehicles:
- Old gearing preset values with Race engine: 5.0 - 6.0 - 7.0 - 8.0 - 9.0
- New gearing preset values with Race engine: 4.0 - 5.0 - 6.0 - 7.0 - 8.0

Reworked gearbox preset's gearing of nearly all non-V8 vehicles:
- Old gearing preset values with Race engine: 5.0 - 6.0 - 7.0 - 8.0 - 9.0
- New gearing preset values with Race engine: 4.0 - 5.0 - 6.0 - 7.0 - 8.0

Tweaked some AI templates' PI* for Class C/D
Added AI templates to Starbeast SS, Venom and Super Venom for all classes.
*Perfomance Index

Make sure almost all suported vehicles reach maximum Perfomance Index of 299 PI.
Swapped engine notes and reworked engines for Rebelrat and Sandstorm.
Reverted minimum weight (kg) of Speedbird GT and Rebelrat to their vanilla values (1.274 and 1.498).
Make sure most non-DLC AI templates almost reach peak value of their respective classes.
- D: 99
- C: 164
- B: 234
- A: 299

Increased engine output of dozens of vehicles to reach Perfomance Index (PI) of 299:
- Killerbee S, Killerpig, Gremlin, Boomer RS, Tristar, Bulldog, Buggy, Bugzilla, Sunrise Super, Hammerhead RS, Nexus RX, Firefly, Speedemon, Double Decker, Hornet, Raiden RS, Stellar, Gorbie, Trooper, Trophy Runner, Battle Bus, Eagle R, Step Van, Motorhome, Supervan.
- Rammer RS, Starbeast SS, Roadslayer GT, Dragslayer, Hunter Panther, Rocket RX, Super Venom.

Increased engine output of some vehicles:
- Killerbee, Boomer, Hammerhead, Speedie.

Added Eagle R to the roster.
- Renamed and reworked engines.
- Added Class D engine.
- Reworked gearbox presets and decreased number of gears to 5.

Fixed issue where only Racing AI vehicles were present in A Class Derby events.
Massively increased AI vehicle variety in Class D Racing/Derby events.
Changed gearbox preset to "extra-short" (1) for non-DLC Derby AI vehicles.
Changed gearbox preset to "short" (2) for non-DLC Racing AI vehicles.
Added the following vehicles to Custom Event mode for Derby/Racing modes in all classes:
- Rammer RS
- Roadslayer GT
- Boomer RS
- Hunter Panther
- Hammerhead RS

- Adjusted gearbox presets for the following vehicles:
- Bugzilla
- Pocket Rocket
- Battle Bus
- Big Rig
- Doom Rig
- Double Decker
- Harvester
- Hellvester
- Lawn Mower*
- Motorhome*
- School Bus*
- Supervan*
- Honey Pot

* Loaner included