* fhandler_console.cc (get_nonascii_key): Generate ESC prefix

	* fhandler_console.cc (get_nonascii_key): Generate ESC prefix
	for Alt modifier generically for function keys and keypad keys.
	Distinguish Normal, Ctrl, Shift, Ctrl-Shift rather
	than Normal, Ctrl, Shift, Alt, so that in combination with generic
	Alt handling all 8 combinations of these modifiers are distinguished.
	(keytable): Add escape sequences for remaining modified
	function keys as a compatible extension using rxvt escape codes.
	Also distinguish keypad keys modified with Ctrl, Shift, Ctrl-Shift
	using xterm-style modifier coding.