1. Update debugger to not trace RPC code even when calling Queue and

threading modules.  Can debug user code which imports these modules,
   though.
2. Re-enable debugger in PyShell.
3. Remove old code implementing previous approaches to this issue.

M Debugger.py
M PyShell.py
M rpc.py

Lib/idlelib/rpc.py

@@ -558,8 +558,6 @@ class RPCProxy:
         if not self.__attributes.has_key(name):
             raise AttributeError, name
 
-    __getattr__.DebuggerStepThrough = 1
-
     def __getattributes(self):
         self.__attributes = self.sockio.remotecall(self.oid,
                                                 "__attributes__", (), {})