Fix SEGV for invalid PQFs and SRU/SOLR targets
Also refactor a bit the code that converts from PQF to SRU/SOLR queries.
-Fix pz2.js: "null object" due to change pazpar2 XML in bytarget result
+Fix pz2.js: "null object" due to change in in bytarget result XML.
-Fixes in tmarc.xsl: Subject shorten for extra commas only.
+Fixes in tmarc.xsl: Subject-long shorten for extra commas only.
Added this normalization to the other subject-long fields (d6xx),
where it was missing.