PGM to STL via Python

A script written in Python (version 2.7) for reading as ASCII PGM file, and then writing an STL "surface" from it.

After playing with the PGM to OpenSCAD surface script, I was disappointed to find that OpenSCAD would not create the STL files for images larger than about 200 pixels square. So, I did what any hack programmer would do, I wrote my own script to bypass OpenSCAD and go straight to an STL file! Voila!