FanLib V1.1 [20150113] - OpenSCAD Library for Muffin Fans

Version 1.1 - Added 2510 and 2515 Fan models as per eagebhart feedback (but with screw size 3mm - holes are designed for screw to go thru not to embed the screw). Again lightly tested.

When I was making my [Carbon Air Filter](http://www.thingiverse.com/thing:112734), I needed dimensions for a Fan to cutout the air hole and screw holes. So I went overboard and collected a whole bunch of sizes, then hey-presto FanLib, an OpenSCAD library to help draw Computer/Muffin fan shapes/sizes.

Arrgh