LP#1698206: Indicate broad searches and heavy facets

LP#1698206: Indicate broad searches and heavy facets

There is a configurable, pagable limit on hits, defined by the superpage
size and max superpages.  When the hit count equals this (by default,
100000) we add a '+' to the hit count to show that there are even more hits.

Facets are calculated per superpage, and if the facet use count equals the
number of superpages seen so far multiplied by the superpage size, we
likewise add '+' to indicate that there are likely more records matching the
facet.

For facets, a user can page far enough to increase the visible number, if
they cross superpage boundaries.

Signed-off-by: Mike Rylander <miker@esilibrary.com>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
Signed-off-by: Kathy Lussier <klussier@masslnc.org>