M RemoteDebugger.py
M rpc.py

Fix the incorrect shell exception tracebacks generated when running
under debugger control:

1. Use rpc.SocketIO.asynccall() instead of remotecall() to handle the
   IdbProxy.run() command.
2. Add a 'shell' attribute to RemoteDebugger.IdbProxy to allow setting
   of ModifiedInterpreter's active_seq attribute from RemoteDebugger code.
3. Cleanup PyShell.ModifiedInterpreter.runcode() and remove ambiguity
   regarding use of begin/endexecuting().
4. In runcode() and cleanup_traceback() use 'console' instead of 'file' to
   denote the entity to which the exception traceback is printed.
5. Enhance cleanup_traceback() so if the traceback is pruned entirely away
   (the error is in IDLE internals) it will be displayed in its entirety
   instead.
6. ModifiedInterpreter.runcode() now prints ERROR RPC returns to both
   console and __stderr__.
7. Make a small tweak to the rpc.py debug messages.