Ring Band creation script

This OpenSCAD script will generate a plain wedding band style ring.
Most parameters are user selectable such as the ring profile shapes.
This would be ideal as the basis for a wedding ring...

Potentially very useful when combined with the following:
Ring metal cost calculator thingiverse.com/thing:12589
Ring Size System Coversion thingiverse.com/thing:12689
for creating and costing a custom wedding band or other such tomfoolery.

Author: Mark Gaffney
Version: 1.4
Date: 2013-03-19

Todo:
Implement texturing
Implement hallmarking

Warning:
Let the right one in

Changes from previous versions:
1.4
- added ellipse_intersection.scad code for 2 new cross section shapes (cs_ellipse_intersection & cs_rounded_ellipse_intersection)
- added support for write.scad on inside or outside of ring, engraved or raised
1.3
- Xxxxx's wedding ring version (no stone, no mount)
1.2
- Made higher resolution shapes by increasing rotate extrude $fn from 50 to 100 and shape $f