[OpenSCAD] Minkowski sum slowness

[Giles Bathgate]

Sorry guys, all these features and patches are for the bleeding edge version.

I compiled the head revision (420c36603b8ba8e7fcf2) on master from source:

https://github.com/openscad/openscad/commits/master

As far as I know there are no official binaries for openscad since May
last year.
Marius told me that a release should be very soon now, they are just finishing
up fixing the build on Windows, which they are migrating to use Visual Studio.

Prehaps Marius would like to give us all an update on this

Regards

Giles