Ignore default properties when loading multilabel images
Summary:
- Add forgotten call of InitializeDefaultMetaDataKeys() to ctor
- Fix names of default properties (. instead of _)
Fixes T29274
Test Plan: Tested manually.
Reviewers: floca, O1 MITK Reviewer Group I
Reviewed By: floca, O1 MITK Reviewer Group I
Maniphest Tasks: T29274
Differential Revision: https://phabricator.mitk.org/D707