+Zebra reads (non-standard) attribute 10 for RPN queries. The value, when
+specified, is returned as subqueryId in SearchResult-1. It un-specified
+no subqueryId is part of SearchResult-1.
+
+Added 'dbperms' setting to zebra.cfg. Names file with lines of
+format username: db1+...dbn, listing databases that user has access to.
+Database-specific access control only happens for searching, at present.
+
Added zebra_set_approx_limit for a ZebraHandle (session). Results
will be approximate if hit count is greater than the limit specified.