[xml] Deleting unused internal entities

[Dustin Voss <d_j_v mac com>]

Hello. I am creating a tree with a number of internal entity definitions and I am using the XML_PARSE_NOENT 
option. The resulting document has an internal subset that defines these entities, but they are never used in 
the actual document.

What's the best way to remove those unnecessary definitions? I do not want to remove the entire internal 
subset, because there may be external entities defined there.

Is it enough to delete nodes from xmlDoc->intSubset->children, or do I have to remove the entities from the 
xmlDoc->intSubset->entities hash table as well? Will xmlDoc->intSubset->next have anything of interest?

To delete nodes, I don't see an xmlDeleteNode function, but I do see xmlReplaceNode. Can I pass in NULL for 
the "cur" parameter?

To access the entity hash table, can I just cast xmlDoc->intSubset->entities to xmlHashTablePtr and call 
xmlHashRemoveEntry? What should I pass for the "f" parameter?

Thanks.