Description: 
Currently, the tag lib descriptor can be edited either using the "Open" action
which shows the .tld file in the source editor, or the "Customize" action which
shows the details in a customizer window.  Other XML files can be edited
with the XML module's editor, the TLD file is currently an exception.

Suggested Fix: 
Add an "Edit" action to the TLD node that opens the XML editor.  This action
would only appear if the XML module is installed.

Evaluation: 
This would be a nice thing to have, as long as the users can still 
edit it as a straight text file. 

The current XML editor doesn't handle comments very well, and there is
semantic data kept in xml comments in the TLD files. 

We don't have time to do this for Orion

A comment.