Replaced multiple query methods with a single more generic query method, and added type synonyms for Subject, Predicate, and Object to make things more readable in AvlGraph.
Replaced multiple query methods with a single more generic query method, and added type synonyms for Subject, Predicate, and Object to make things more readable in AvlGraph.

darcs-hash:20071003060809-db1bb-b26256a203f3c8cbf8593d44b85fb1e084347fa9

ddssff/rdf4h,cordawyn/rdf4h,LeifW/rdf4h,jutaro/rdf4h