LP#1117808: new methods for calculating MARC merges

LP#1117808: new methods for calculating MARC merges

This patch adds three new middle-layer methods for calculating
the result of MARC merges.

open-ils.cat.merge.marc.per_profile:

        Calculate the result of merging one or more MARC records
        per the specified merge profile
        @param auth The login session key
        @param merge_profile ID of the record merge profile
        @param records Array of two or more MARCXML records to be
                       merged. If two are supplied, the first
                       is treated as the record to be overlaid,
                       and the the incoming record that will
                       overlay the first. If more than two are
                       supplied, the first is treated as the
                       record to be overlaid, and each following
                       record in turn will be merged into that
                       record.
        @return MARCXML string of the results of the merge

open-ils.cat.merge.biblio.per_profile:

        Calculate the result of merging one or more bib records
        per the specified merge profile

        @param auth The login session key
        @param merge_profile ID of the record merge profile
        @param records Array of two or more bib record IDs of
                       the bibs to be merged.
        @return MARCXML string of the results of the merge

open-ils.cat.merge.authority.per_profile:

        Calculate the result of merging one or more authority records
        per the specified merge profile

        @param auth The login session key
        @param merge_profile ID of the record merge profile
        @param records Array of two or more bib record IDs of
                       the bibs to be merged.
        @return MARCXML string of the results of the merge

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>