Update Ribbon Algorithm

There were a couple of mistakes in the implementation of my ribbon algorithm currently in Narupa iMD, which led to ugly bulges and incorrect shading of normals. This fixes them and brings Narupa iMD in line with how I describe the algorithm in my paper.

This is important because I need to link to the exact version with this implemented correctly before I submit my finalized manuscript for the paper.

It also updates the colors to not be ugly default colors, but based on the colors used by the RCSB to color their secondary structure.

Original Ribbons

Updated Ribbons