Add set_defaults! and set_overrides! Dataset mutation methods

lib/sequel_core/dataset.rb

@@ -52,7 +52,8 @@ class Dataset
     group group_and_count group_by having inner_join intersect invert join
     left_outer_join limit naked or order order_by order_more paginate query reject
     reverse reverse_order right_outer_join select select_all select_more
-    set_graph_aliases set_model sort sort_by unfiltered union unordered where'.collect{|x| x.to_sym}
+    set_defaults set_graph_aliases set_model set_overrides sort sort_by
+    unfiltered union unordered where'.collect{|x| x.to_sym}
 
     NOTIMPL_MSG = "This method must be overridden in Sequel adapters".freeze
     STOCK_TRANSFORMS = {