updated for version 7.3.1288
Problem:    The first ":echo 'hello'" command output doesn't show.  Mapping
	    for <S-F3> gets triggered during startup.
Solution:   Add debugging code for the termresponse.  When receiving the "Co"
	    entry and when setting 'ambiwidth' redraw right away if possible.
	    Add redraw_asap().  Don't set 'ambiwidth' if it already had the
	    right value.  Do the 'ambiwidth' check in the second row to avoid
	    confusion with <S-F3>.
Added tag v7-3-1288 for changeset 8b7baf39a345