Beta Wentward Powertrain Mod 2.3

Adds the 6 and 4 speed transmissions we know from the wentward (B300 in real life) but this time it has torque converter behaviour (watch allison buses on youtube, they lock the torque converter midway through 2nd gear, allowing for better shift)

this is in the following new presets:
Skoolie - 4 speed form
InterCity MK2 - Allison - 6 speed form

I know that it's a bit janky having a duplicated gear, that's just the way it is, hence 2nd locked is 3rd, and gears beyond that are wrong on the display selector screen.. (also in manual mode, it's odd having the same gear twice)