authorities: start of work on reindexing

authorities: start of work on reindexing

Currently, MARC authorities are indexed (assuming Zebra
is used) with Zebra's GRS-1 module.  However, it does
not appear to be possible to index phrases that cross
subfield boundaries using the GRS-1 module's records.abs
config file's melm, elm, and xelm directives.

Since it is necessary to be able to efficiently search
an entire authority heading (e.g., to see if a given
bib heading is authorized), I'm proposing a switch
to Zebra's DOM XML filter module, which uses XSLT
to generate the words and phrases to be indexed from the
original MARC XML (or ISO2709) record.

The file authority-zebra-indexdefs.xml is an XSLT stylesheet
to implement the new indexing regime.  It is based on the
MARC21 authority record.abs with the following changes:

  * addition of 148/448/548
  * changed name of "see" indexes to "see-from"
  * changed name of "see-also" indexes to "see-also-from"
  * added index on the subject thesaurus based on
    the 008/11 and 040$f
  * added indexes on the full heading

authority-zebra-indexdefs.xml was generated from
authority-koha-indexdefs.xml via the XSL transform
koha-indexdefs-to-zebra.xsl.  authority-koha-indexdefs.xml
is the actual master version of the indexing definitions,
and was created to provide a much more compact syntax
over the raw XSLT that is to be passed to Zebra.

An experimental schema for Koha indexing definitions is
under way; my aim is to propose a simple format that can
be readily worked with, and perhaps even generated as
a serialization of indexing definitions that are set up
via administration settings in the Koha database itself.

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