Tof's Customizable Flange - Parametric

Needed a flange to connect the hose for my shopvac to the vacuuformer I'm building, figured I'd make it parametric for anyone who wants to customize.

2016-10-14 Heavily overhauled the script for this thing, now you can choose whether or not you want a fillet, and whether you want the screw holes to be countersunk.