[3dprinter-general] New build system for Cura

[Gregor Riepl]

> Looks like they're using cmake + ninja now.
> 
> I hope this will work with pybuild. If it does, it should automatically 
> pick up the right Python version, or do a multi-version build as needed.
> 
>> If someone with more clue than me about sip (is that still needed?),
>> cmake, and pybuild could pick that up, that would be nice.

I may have been way too optimistic. :(

ninja-build is available in Debian, but Ultimaker has also started using 
conan, which is not packaged yet. So, we can't proceed until 
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=845463 gets fixed.

It's also very likely that a lot of integration work will be needed, as 
conan seems to be tailor-made for the JFrog CI/CD system and its 
artifact storage. We'll see how well it plays together with the 
standalone package management system in Debian.