trigger trhottle for e-scooter

Cleaned up unwanted stick-outs,
made the over-pull stop,
made holes for the return spring.
This may be the final version.

This is the result of 4 redesigns and several reiteration loops to get here : any appreciation to the effort that went in this project is welcome.
The stl compensates 0.5mm for internal measurements that my old slicer cannot compensate.