Eliminated "handled" field in Parser::Action

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).

src/terminal/terminaluserinput.cc

@@ -39,8 +39,6 @@ using namespace std;
 string UserInput::input( const Parser::UserByte *act,
 			 bool application_mode_cursor_keys )
 {
-  act->handled = true;
-
   /* The user will always be in application mode. If stm is not in
      application mode, convert user's cursor control function to an
      ANSI cursor control sequence */