Deleting a tagset and adding a new one causes the old tagset to reappear

[possibly]

The issue is caused by the way the underlying python grammar.py def add_new_markup_set works. If any nonterminal contains a reference to a tag (and thus the tag's tagset), the tagset will magically reappear when adding a new tagset.

Probably the fix should be that when grammary.py def delete_tagset is called, all nonterminals are stripped of any reference to any tags that are in that tagset.