(+superclass): New method.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@222 72102866-910b-0410-8b05-ffd578937521

Source/NSObject.m

@@ -148,6 +148,11 @@ BOOL NSDecrementExtraRefCountWasZero(id anObject)
   return [self mutableCopyWithZone: NS_NOZONE];
 }
 
++ (Class) superclass
+{
+  return class_get_super_class(self);
+}
+
 - (Class) superclass
 {
   return object_get_super_class(self);