Made a number of tweaks to the way the search currently works, but principally worked on generic code in the hcmc/xquery/xq-utils.xqm library to convert user-friendly search-box input into the XML syntax that eXist can use to talk to Lucene. This seems to be working well, although I haven't yet found a way to put it into practice because we're still using a string-construct-and-eval approach to filtered queries. It may be just a case of using the XQuery serialize() function.