Modify RoutingEntryForm.has_changed to ignore changes to the group so that extra forms aren't mistakenly seen as modified.
Merge branch 'develop' into feature/issue-963-allow-saving-group-router-without-adding-more-groups
Empty initial group selection and tests for various invalid group configs.
Merge branch 'feature/issue-963-allow-saving-group-router-without-adding-more-groups' into develop