Cutout for the illumination cable

I've made a hole at the front of the Z cable tidy for the illumination cable. Doing this meant figuring out a bunch of the transforms. I have added comments as I went. I also needed to get the rendering working on my computer, and have added a README in case it helps others in the future.

This MR allows the microscope to be assembled without cutting the front cable tidy. It is not the neatest solution because the cable is exposed, but it will do for now.