Fixing how we calculate and lay out the holes of the end mills

Signed-off-by: Scanner <scanner@apricot.com>
Playing with a different kind of end mill box..

The idea is to have it be mostly open air with just holders for the end mills themselves enclosed.. to help reduce warping when printing with ABS.

NOTE: this does not work right now, and I might abandon it!
Signed-off-by: Scanner <scanner@apricot.com>
Reworked the logic for the end mill holes and how the box is centered. A bit simpler now. Can now also finally render 1x1 boxes.

Signed-off-by: Scanner <scanner@apricot.com>