Experimental Z axis combined leadscrew base

This is an experimental Z axis combined leadscrew base for the Mendel. It's been modified to reduce the number of printed and non-printed parts necessary, and also to parameterize the length of the available Z motor adjustment slots.

I've integrated a Z bar clamp into the body of the leadscrew base, which utilizes the frame bar and nuts holding the leadscrew base in place to clamp the Z bar in place as well. This design was inspired by Whosawhatsis' parameterized Huxley work.

I've includ