Performance: added cache of known valid classes in AnnotationChecker.
Fixed collection lazy loading: usage of Set as default collection implementation forced object loading by delegation of calls to hashCode() and equals() upon proxy insertion in collection. ProxyHandler now takes care of those methods, solely using the object URI.
Added debug traces to RepositoryDataSource.
Removed duplicate control in assertSupported() that are already performed by AnnotationChecker.assertValid(). Added persist(Object, boolean) to bypass object existence test in MergeCascade.
Query optimizations in DataSourceUtil. Made use of TripleSource.getStatements() in describe().