CURA-6019
All plug-ins now have to re-check whether they are still compatible with the current version of Cura. Contributes to issue CURA-6019.
CURA-5627
CURA-4451 - Add upgrade script for 3.0. to 3.1 - Upgrade old stack files so they will use "empty_quality" as the "Not Supported" quality profile. - Increase SettingVersion to 4