add decent method to get the programs return to interpreter

only had such methods in tests, but they really belong in code
also adding fake values to true ,false and nil

test/parfait/test_integer.rb

@@ -54,5 +54,20 @@ module Parfait
       assert_equal 33 , addr.value
     end
   end
-
+  class TrueTest < MiniTest::Test
+    def test_true
+      assert TrueClass.new
+    end
+    def test_set
+      tru = TrueClass.new
+      assert_equal 20 , tru.set_internal_word( Integer.integer_index , 20 )
+      assert_equal 20 , tru.get_internal_word( Integer.integer_index )
+    end
+    def test_get_true
+      assert_equal 1 , TrueClass.new.get_internal_word( Integer.integer_index )
+    end
+    def test_get_false
+      assert_equal 0 , FalseClass.new.get_internal_word( Integer.integer_index )
+    end
+  end
 end