refactor: initialize UserLayoutChannelDescription parameters at declaration

Initialize parameters Hashtable at declaration rather than inline in constructors.
make UserLayoutChannelDescription toString() more complete

Reflect more of channel description state in toString(), making logging of channel descriptions more useful.
Copy DLM attributes in UserLayoutNodeDescription copy constructor.

Without the fix to `UserLayoutNodeDescription`, the assertions that DLM attributes copied fail in included unit test.
Fix UserLayoutChannelDescription copy constructor to copy Node attributes.

Switch UserLayoutChannelDescription copy constructor to invoke superclass copy constructor so as to copy superclass-managed attributes.  Exercised by included unit test.  Test of copy of Node attributes fails without this fix.
Only invite un-favoriting of user-deletable nodes.

Reflect in the `edit.jsp` whether items can be un-favorited.  Detect in controller when attempts to un-favorite will fail for lack of permissions.