TODO

Code that could be integrated:
* http://github.com/l0b0/qr2scad
* http://github.com/l0b0/img2scad
* http://github.com/l0b0/OpenSCAD-Minimizer
* http://www.thingiverse.com/thing:4656
* http://www.thingiverse.com/thing:4758
* http://www.thingiverse.com/thing:6021
* Color library: http://www.thingiverse.com/thing:6717
* http://www.thingiverse.com/thing:6465

Integrate these better:
* bitmap

Testing:
* add tests for openscad functions
* motors.scad
* tests for 2D stuff

Code style:
* motors.scad
* nuts_and_bolts.scad