Parametric track compatible with standard wooden train track

Parametric module to create a piece of track for Thomas- and Brio-compatible wooden train sets. Parameters allow for straight or curved track as well as combinations (switches or points), including recommended measurements based on wooden track for "small" and "large" curves.
 
To render this shape, you will need [tracklib.scad](http://www.thingiverse.com/thing:216915) installed in the same directory as this file, or the [dotscad/trains](https://github.com/dotscad/trains) repository clone