New calculations to determine the average shrinkage when two materials are used. By default the material shrinkage is set to null (None). In that case the shrinkage of that material is not taken into account in the new averaging formula. Support materials such as PVA, BAM, Aquasys etc. should keep this setting to null. When two materials are used with a shrinkage percentage the average of these two materials will be used.
Relates to PP-77
Should've done this in the merge, but I just increased the setting_version for these.
I also removed a deleted setting from the advanced visibility. We don't have tests that ensure that these visibility presets are good. Lucky I found it then, with a Ctrl+Shift+F search.
Also convert the values for prime_tower_min_volume to make it behave similar to what the minimum volume used to be. This feature fixed a bug with the computation from volume to thickness. Now it's correct but we have to correct the old values to be still the same (approximately) as what used to be the end result.
Contributes to issue CURA-5457.
