3d printer: That was a bitch and a half, but it works

Construction takes about 2 full days. Main things to watch out for:
* Tension your belts at the time you install them, not at the end. Waiting till the end means disassembly.
* Have a magnet handy to hold things in tight spots.
* Be extra careful when building the X-Y axis piece, it's the hardest to get at when you're done.
* This is hardware, not software. It really is 10x more time to fix it after the fact than to do it right the first time.

That said, ever part works. The software can talk to the motors, the heating elements, etc. The end switches work. The firmware update worked. It all looks good and I've done basic tests of everything.

Next step:
* Run the heating elements to 220 deg C and do some practice extrusion.

Assuming it passes that... we're ready to try our first test print.