- Change the XCQL output to include the nasty and redundant

	  (but official) <leftOperand> and <rightOperand> wrapper
	  elements.
	- Change the XCQL output to use the nasty (but official)
	  rendition of prefix-mapping: a <prefixes> element,
	  containing one of more <prefix>es may appear at the top
	  level of either a <searchClause> or a <triple>.
Also, improve the text/regression scaffolding somewhat.