Proper support for 2D packing across multiple sheets

[mbugert]

[dogtopus]

Any news on this?

[dogtopus]

So I did some refactoring (mainly replacing the inline ifelse ladder to key-value pairs since IMO the former is very ugly) and added support for multipage support and rotation. You can find my changes here: https://github.com/dogtopus/laserscad/tree/experiments

I also wrote an alternative layout script based on rectpack. It doesn't require make and only generates 1 temporary file (the .echo file from OpenSCAD) in system temp directory, thus should work on Windows given a working Python 3 installation.

Let me know if you think it's good to mainline these changes.