Customizable door holder

A customizable door holder inspired by this design: https://www.thingiverse.com/thing:946304

I've design it from scratch using OpenSCAD, so you can use Thingiverse's customizer or change the OpenSCAD file yourself to suit your own door.

You only need to change these 5 parameters:
- thickness: overall thickness of the door holder.
- height: overall height of the door holder, currently set to 16mm for use with an M size command strip.
- width: how long your base are. Currently set to 52mm for use with an M size command strip.
- hook_size: size of the hook holding your door
- length: distance from wall to the outside (furthest side) of your door

V2 change:
- Added easy_release parameter that will create a curve so it will release when pulled with enough force. Without this the door will be firmly hold in place.