Resource Conflict node_type form incorrectly maintains a list of node types, patch attached

Currently if you enable conflict checking for a node type it will add it to the array rc_types.

If you then disable conflict checking it does not remove the content type name from the array.

If you simply edit the content type without disabling conflict checking it adds the content type into the array again so conflict checking routine runs another time, or however many times you've edited the content type!

I've attached a patch which resolves this issue.