kohabug 1621 - add subtitle to main results and details pages

kohabug 1621 - add subtitle to main results and details pages

Including the subtitle in search results and OPAC and staff
details templates.  The subtitle is expected to be in the
MARC subfield that is mapped to the (now nonexistant) column
bibliosubtitle.subtitle.

This is a fairly hackish patch that is meant to be minimally
disruptive while allowing subtitles to be displayed for those
not using the experimental XSLT bib display feature.  It
does *not* cover all cases where you have a MARC
record and want to display its subtitle.

UNIMARC notes: at the moment, none of the fr-FR UNIMARC
frameworks appear to be map any subfields to bibliosubtitle.subtitle.
This could be changed, but caveat programmer: the UNIMARC 200$e
is repeatable (meaning that get_koha_field_from_marc will put in ' | '
between multiple subtitles) and one may want to also include the
200$d (parallel title).  A GetMarcSubtitle routine may be in order
if absolutely necessary.

This points to a long-term need to make display of MARC (and later, hopefully,
non-MARC) bib records more flexible - the XSLT feature is one approach;
there may be others.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>