rename typed_method to callable_method

seems to make the essence clearer
also extracted base class

test/vool/send/helper.rb

@@ -35,7 +35,7 @@ module Vool
         assert_equal Mom::SimpleCall,  @ins.next(2).class
     end
     def test_call_has_method
-      assert_equal Parfait::TypedMethod,  @ins.next(2).method.class
+      assert_equal Parfait::CallableMethod,  @ins.next(2).method.class
     end
     def test_array
       check_array [Mom::MessageSetup,Mom::ArgumentTransfer,Mom::SimpleCall] , @ins

test/vool/send/test_send_self.rb

@@ -18,7 +18,7 @@ module Vool
       assert_equal SimpleCall,  @ins.next(2).class
     end
     def test_call_has_method
-      assert_equal Parfait::TypedMethod,  @ins.next(2).method.class
+      assert_equal Parfait::CallableMethod,  @ins.next(2).method.class
     end
     def test_call_has_right_method
       assert_equal :get_internal_word,  @ins.next(2).method.name