TurtleParser.hs: cleanup and refactoring.
TurtleParser.hs: cleanup and refactoring.

darcs-hash:20071104045749-db1bb-4352c74b4f8b8d4b6a8defff09d53245a653adc3

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