Better PTree: PTree can now take any key type, and does not duplicate.

 * BUGFIX: Fixed a bug where if the tree contained some string, `w`, and
   another string `wx` for some string `x`, that filtering by `w` and
   iterating would produce a sequence <w, wx, w>.
 * Also allowed FilterList to take any string as a key and have it
   supported by the iterator.
Better PTree: Adding spaces to Node List names.

Also modifying textbox to allow spaces.