Wilson II

This is the Wilson II, it is a new design based on the Wilson TS. Some of the design changes are:

* All smooth rods upgraded from 8mm to 10mm.
* Z axis threaded rods replaced with 8mm lead screws.
* Upright frame consists of two sets of vertical beams and two beams beneath the Y axis, for greatly improved rigidity.
* 50% larger default build volume.

Please note that as of this revision, the rod-to-rod and rod-to-threaded rod spacing is no longer identical to the Prusa i3. These changes were necessary to accommodate the threaded rods and the larger smooth rods. The impact of this is that you can't necessarily just use parts designed for one on the other.

The design files are all on github: https://github.com/mjrice/Wilson2
And assembly videos are on YouTube: https://www.youtube.com/playlist?list=PL8Y-7ekQy0fSyEhXliN7lWew1VU0zqvaN