Bug 29185: Facilitate searching for cnum

Instead of typing the case sensitive Control-number each time.
4 strikes instead of 15 on your keyboard. Wow! Gain of 73%.

Test plan:
Copy ccl.properties to /etc/koha/zebradb, restart Zebra and
search for cnum=SOME_ID in opac or intranet.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

C4/Search.pm

@@ -1009,6 +1009,7 @@ sub getIndexes{
                     'Conference-name-seealso',
                     'Content-type',
                     'Control-number',
+                    'cnum',
                     'Control-number-identifier',
                     'cni',
                     'copydate',

Koha/SearchEngine/Elasticsearch/QueryBuilder.pm

@@ -82,6 +82,7 @@ our %index_field_convert = (
     'notes' => 'note',
     'rcn' => 'record-control-number',
     'cni' => 'control-number-identifier',
+    'cnum' => 'control-number',
     'su' => 'subject',
     'su-to' => 'subject',
     #'su-geo' => 'subject',

etc/zebradb/ccl.properties

@@ -986,6 +986,7 @@ ext 4=1 6=3
 ###
 # Koha Local-Use Biblio Indexes
 Control-number 1=9001
+cnum Control-number
 biblionumber 1=9002
 totalissues 1=9003
 cn-bib-source 1=9004