WebSearch: type and field codes
- updated SPIRES mappings to reflect different indices for type and field codes and journal codens
- tests for same (fixes #506)(fixes #521)
- changes behavior of bibknowledge slightly so that exact kbr search by key, for the empty string, returns hits only if the empty string is actually a kbr key.
- and tests for this behavior
Co-authored-by: Joe Blaylock <jrbl@slac.stanford.edu>