Add _s custom literal for durations
Add _s custom literal for durations

You can indicate that something takes 5 seconds by writing 5_s now. We can't make a literal saying '5s' because custom literals need to start with an underscore because C++ reserves the rest for use in future C++ versions.

Contributes to issue CURA-4410.

Ultimaker/CuraEngine,Ultimaker/CuraEngine