fixed attr_*: forgot '@'

mrblib/class.rb

@@ -2,14 +2,14 @@ class Module
   # 15.2.2.4.13
   def attr_reader(*names)
     names.each{|name|
-      define_method(name){self.instance_variable_get(name)}
+      define_method(name){self.instance_variable_get('@'+name.to_s)}
     }
   end
   # 15.2.2.4.14
   def attr_writer(*names)
     names.each{|name|
       aset = (name.to_s+"=").intern
-      define_method(aset){|v|self.instance_variable_set(name,v)}
+      define_method(aset){|v|self.instance_variable_set('@'+name.to_s,v)}
     }
   end
   # 15.2.2.4.12