Inner Bevel between any (convex) Shape and a Plane In OpenSCAD

This is an OpenSCAD module that creates an inner bevel between any (convex) part and a plane at z=h. Please note that the part does not have to be perpendicular to the z-plane. The bevel will be h_bevel high and r_bevel wide. For h_bevel equal to r_bevel the bevel will have circular cross section in the plane(s) perpendicular to the z-plane.
The number of faces of the bevel along its cross section is given by fn_bevel. For fn_bevel=1 this will be a linear bevel. The 'roundness' of the bevel al