Morpho

I think we can be more clever with mixing and matching the selection combobox with MNodeSelectionObjects (listed from the CN) and String URLs (manually entered). We only save the MN URL in the configuration file, so we'd rely on matching that up with the list from the CN. We can't store nodeId since an unregistered MN will not have one and we really do need the URL, not just a random [unregistered] nodeId in the Morpho config.