Implement class instance variables

as they are just the type of the meta_class, that was relatively simple.
I feel this is what oo is meant to be, instance variables and methods for the objects, and since classes are objects, for them too.
Class variables seem like a design mistake, weird scoping rules and no data hiding (left as an exercise to the reader)

lib/parfait/class.rb

@@ -33,7 +33,7 @@ module Parfait
       @name = name
       @super_class_name = superclass
       @instance_methods = List.new
-      set_instance_type( instance_type )
+      @instance_type = instance_type
       @meta_class = MetaClass.new( self )
     end
 
@@ -65,13 +65,6 @@ module Parfait
       @instance_type = @instance_type.add_instance_variable( name , type )
     end
 
-    # setting the type generates all methods for this type
-    # (or will do, once we store the methods code to do that)
-    def set_instance_type( type )
-      raise "type must be type #{type}" unless type.is_a?(Type)
-      @instance_type = type
-    end
-
     # return the super class, but raise exception if either the super class name
     # or the super classs is nil.
     # Use only for non Object base class