Increased readability for parent/child mapping

Display the decoded value of objtype for the parent/child object and group the display by type instead of listing "Container(s)" or "Contains".

This especially increases readability for VM/Cluster mappings as the VMs are separated from the Servers. Also, if used with custom ObjectTypes, this makes for a nice distinction between different Parent/Child types (e.g. we're using an object-type SupportContract to list our contracts and map objects to them.)