make MSRPChat new-style class

darcs-hash:20090226084436-b2873-ad931cc28d7359e13c6e05fe462acea674b6dc79
remove __del__ method from MSRPChat (use end() explicitly)

darcs-hash:20090226084502-b2873-9edabefea0f79e40c22a8e513a4d86a81d76fec0