gearbox generator for OpenSCAD

Gearbox generator library for OpenSCAD.
https://github.com/sadr0b0t/gearbox

also available from Openscad-Modules repo
https://github.com/RobertFach/Openscad-Modules

~~~
spm install gearbox
~~~

10may2018: update script file: add more configurable params, draw base and cover as arbitrary polygon.

~~~scad
use

gb_gearbox(base=true, cover=true, gears=true,
mirror_x=true, mirror_y=false,
printed_rods=false,
exit_base=true, exit_cover=false,
tnum1=[9, 12, 12], tnum2=[47, 47, 47],
cp=[1.5, 1.5, 1.5], pa=[20, 20, 20],
holed1=[2, 2, 2], holed2=[2, 2, 2],
h1=[9, 5, 5], h2=[3, 3, 3],
a=[-25, 15, -15], stage1_c1=[0,0],
rot2=[0, 0, 0],
h2_gap=1, bottom_gap=0, top_gap=1,
base_points=[[-54, -20], [-54, 10], [54, 10], [54, -20]],
cover_points=[[-54, -20], [-54, 10], [54, 10], [54, -20]],
base_h=3, cover_h=3,
columns=[
[0, -15],
[49.5, -15], [49.5, 5],
[-49.5, -15], [-49.5, 5]],
bas