Customizable Hirth Joint (CSG version) (library)

Customizable Hith Joint (CSG version) (library)
This is an improved version of
http://www.thingiverse.com/thing:387292
This improved model can start the teeth not just at the center but also at a polygon of choosable radius. Meaning one can create thin walled tube couplings that are radially self centering (Such couplings are often found in Mountainbike axles).
The interpenetration depth of the teeth can be limited with the flatlimit parameter.
## Specialised functions
hirthaxle(l,d,