reinstate DOM+XPath stuff by using XPathManager and XMLInfrastructure. Simplify the xpaths used in patchers by making them more explicit (to avoid scanning a bunch of paths that are irrelevant). Turn off locking in the carto event manager impl, since this caused spawning of MANY threads. Collect mapping of GAV => accepting-filter-children-set from discovery results, then iterate the accumulated map (which could result from multiple discovery threads) to create the next wave of discovery-todo's