changed local storage mechanism

- moved from a Dictionary<string, string> to a
Dictionary<Tuple<string,string>, XElement>.  The new dictionary now keys
off of the element.name.localname property and the unwrapped jQuery
selector, combined with the associated element itself.
- changed the finalXDoc generation to be based off of the new _itemDict
instead of the List of elements as the deduping process using the
_itemDict.  this solved a funky dupe bug.