rename singleton_class to single_class and misc

was clashing with real ruby method name
also many superclass mismatch fixes
some misc

test/mains/source/classname_Space_5.rb

@@ -1,4 +1,4 @@
-class Class
+class Class < Behaviour
   def name
     @name
   end

test/mains/test_new.rb

@@ -16,7 +16,7 @@ module Mains
 
     def whole_input
       <<-eos
-        class Class
+        class Class < Behaviour
           def get_name
             @name
           end