Websearch: IRNs can be numbers or strings

• SPIRES syntax parser now supports arguments of the form 'SPIRES-#' or simply '####' for all of key, irn, record, and document, e.g.: 'find irn 1000039', 'find record SPIRES-1000039', 'irn:SPIRES-1000039' are all equivalent. (fixes #130)