Create Pattern#dup, which will recursively duplicate itself.

Author: gkellogg

lib/rdf/query/pattern.rb

@@ -59,6 +59,12 @@ def initialize!
       super
     end
 
+    ##
+    # Create a new pattern from the quads, recursivly dupping sub-patterns.
+    def dup
+      self.class.from(self.to_quad.map {|t| t.is_a?(RDF::Query::Pattern) ? t.dup : t})
+    end
+
     ##
     # Any additional options for this pattern.
     #