Realistic 18 speed for T-Series v1.0.1

Hello! Here is my first mod. It's essentially a more realistic transmission that mimics the range and divider of a real 18 speed. I based the transmission on an 18-speed Eaton Fuller gearbox. In order to use this mod, you will need to map the separator and range controls to individual buttons (these will be under the car-specific controls for the T series). Essentially, you are using two transfer boxes. I like to match the splitter to the left paddle of my wheel and the range to the right paddle. So you can use your right hand to change gears and your left hand to steer + split gears. You have to change the range a lot less, so you can use your right hand to do it.