Wood frames [CR]

Closes #5328.

Adds wooden vehicle frames, which have the simple trade-off of being half the weight of a steel frame but also have half the durability. They can be crafted with 2x4s and nails. Allows for making lighter, faster vehicles.

Feedback would be appreciated on if the half-and-half tradeoff is fine or if it should be adjusted in one direction or the other.