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
diff --git a/Lib/idlelib/PyShell.py b/Lib/idlelib/PyShell.py
index 483a921..ba898b2 100644
--- a/Lib/idlelib/PyShell.py
+++ b/Lib/idlelib/PyShell.py
@@ -690,7 +690,7 @@
         text.bind("<<beginning-of-line>>", self.home_callback)
         text.bind("<<end-of-file>>", self.eof_callback)
         text.bind("<<open-stack-viewer>>", self.open_stack_viewer)
-        ##text.bind("<<toggle-debugger>>", self.toggle_debugger)
+        text.bind("<<toggle-debugger>>", self.toggle_debugger)
         text.bind("<<open-python-shell>>", self.flist.open_shell)
         text.bind("<<toggle-jit-stack-viewer>>", self.toggle_jit_stack_viewer)
         text.bind("<<view-restart>>", self.view_restart_mark)