An idea to reduce the mass of the x carriage

If the guitar machines are too heavy, the design could be reworked to
use just one for both lines.
All hail nophead.
Remove unused code
Continue moving statics into config.scad
Move motors out to make room for PSU
Default to 8x8x8 size

Start paying attention to rod lengths.  It looks like 8x8x8 should be
doable with huxley-length smooth rods.
X endstop holder on y carriage
Remove dead code
Endstop only on negative side of y carriage