Update - Improved vehicle config and UAZ bounding box bug fixes.

- Non-breaking changes to the check for whether the cursor target is a
  towable vehicle.
- Deprecated the MF_Tow_Towable variable as it is no longer used as a
  check condition.
- Vehicles which can tow and be towed are now maintained in
  MF_Tow_Towable_Array function, removing the need to maintain two
  seperate arrays.
- Updated the install guide to reflect the changes above.
- Fixed the z-axis offset issues with the UAZ as the tow vehicle and as
  the towable vehicle which caused the UAZ to either be in the air or
  under the ground during towing.
- Fixed the player z-axis offset to the UAZ when in an animation state for
  towing. This again was due to the bounding box data on the UAZ being
  completely inaccurate.