Actually the other way around, so we don't have another negation you have to turn on to turn off (and so the default can be false I suppose). The idea is that recently, a feature was introduced where there should be walls instead of normal skin in small hard to reach places of the model. However, this is to be excluded in most cases for all the top-layer parts exposed to air on the buildplate.
implements CURA-10829
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.
