top: prepare for more than two abreast summary display

top: prepare for more than two abreast summary display

I guess the cat's out of the bag with the prior commit
message. It mentioned the objective of displaying more
than the current two cpu graphs on summary area lines.

On the way to that objective, this patch just prepares
our battlefield for the actual implementation in which
up to 8 individual cpu graphs will be shown on 1 line.

[ no logic has been impacted with this commit. we're ]
[ just adding one manifest constant, trading several ]
[ identifiers and updating some comments so the next ]
[ commit might be just a little bit more manageable. ]

Signed-off-by: Jim Warner <james.warner@comcast.net>