Improved Parametric Saddle Clamp

Inspired by sgrabers but added filleting between tabs and saddle, as well as chamfered tabs. Both to improve looks and strength. Fillet OpenSCAD library modules unceremoniously dumped into code from Andrew Plumb's clothbot utilities at https://github.com/clothbot/ClothBotCreations/blob/master/utilities/fillet.scad. The chamfered edge uses the minkowski 3d function to create the chamfered edges on the tabs.

Updated for a rounder screw hole and now works with customizer!