Enhancements/fixes for OPAC advanced search screen

Enhancements/fixes for OPAC advanced search screen

Fixed opac-search.pl for correct test of expanded options and
to pass variable for MARC21 to advanced search screen.

Added Publication Date Range search to advanced search screen

Removed obsolete item type code section from advanced search screen
(wasn't displaying anyway because expanded options wasn't working,
superceded by site-specific item type searches).

Changed wording on Additional Content Types pulldown to make clear
it's limited to Books/Printed Materials -- this is basing off the
008 positions 24-27, but the options (and those positions) are only
valid for Book material types. Other material types have different
008 settings in those positions.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>