This field was used during development to measure the
coverage of the ANSI terminal parser against typical
terminal input sequences.
The "handled" field has not been read by any code since
commit 1ee54cd7 (February 2011). Eliminating the field
by popular request (closes#723).
* Fix inefficient STL use around Parser::UTF8Parser.
* Reduce typeid() usage, change some of it to a virtual method
* Do multiple-line scrolls as a single move
Keith Winstein