Bib record browser with 'see also', etc from linked authority headings

Bib record browser with 'see also', etc from linked authority headings

This feature provides a patron-oriented OPAC interface for browsing
bibliographic records.

Users choose to browse by Author, Title, Subject, or Series. They then
enter a browse term, and the nearest match from a left-anchored search
on the headings extracted for browse purposes will be displayed in a
typical backwards/forwards paging display. Headings link to search
results pages showing the related records. If the browse heading is
linked to any authority records, and if any *other* authority records
point to those with "See also" or other non-main entry headings, those
alternative headings are displayed a linked to a search results page
showing related bib records related to the alternate heading.

The counts of holdings displayed next to headings from bibliographic
records are subject to the same visiibility tests as search. This means
that the org unit (and copy location group) dropdown on the browse
interface affects counds, and it further means that whether or not
you're looking at the browse interface through the staff client makes a
difference.

This builds on the two previous commits that provide inter-authority
linking and the linking of metabib.browse_entry rows to authority
records.

Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>