Chatter Gear Box

Just a quick and dirty hack on MakerBlock's chattering teeth gears. I did switch to the MCAD version of the involute_gear library since I had it installed already.

There is now a module called gear_box() which takes an positive integer as input (I called it 'stages') and replicates a pair of those same gears between the gear holding the spring, and the gear holding the cam.

I also changed the gear ratios slightly to get an even 2 rather than 1.57 and change.

By my math, each gear-to-gea