really fix color breakage by decoupling edit_update() and

really fix color breakage by decoupling edit_update() and
edit_refresh(); edit_update() is only called without edit_refresh() in
do_gotolinecolumn() if allow_update is FALSE, and in edit_refresh()
itself if edittop is out of range of current

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2875 35c25a1d-7b9e-4130-9fde-d3aeb78583b8