Add preliminary gears for extruder
Fix too small gear for planets
Reverse helix angle on planet

We need it to be opposite of the sun
Add carrier options
Fix hub_thickness reference in gears.scad
Add backlash and clearance settings to planet and sun gears
Arrange planet gears nicely to test that they mesh
Add carrier.scad
Reduce sun_hub_d
Shift the carrier hub below

We don't want it to impact the sun gear.
Move carrier hub thickness calculation into options.scad
Add assembly.scad for extruder
Use % on stepper