Parameterized Decaleur

First attempt at a customizable decaleur base. Work in progress, not for real use.

This is a customizable part!

Go to customizer and you can change the handlebar size (25.4, 26.0, and 31.8), the rod size (Ortlieb clamp sizes 16, 12, 10, 8mm) and the overall length.

Uses a standard seatpost bolt for clamping.

Still needs:

- better tangency
- fit tolerancing for holes