Imperial Module for OpenSCAD

Very often I'll see OpenSCAD code like:
````
scale(25.4) cylinder(d=1/2, h=5/8, $fn=64);
````
...to make inch-sized parts. OpenSCAD thinks its making parts 25 times smaller than they are and generates bare-minimum detail unless forced, so $fn gets jammed into every single statement.

$fs can be overrided to overcome that:
````
for($fs=$fs/25.4) scale(25.4) cylinder(d=1/2, h=5/8);
````

This generates a sane number of fragments without being forced! Drop this in a handy module and you get:
````
imperial() cylinder(d=1/2, h=5/8);
````