Fixing bug with jsonrpc._Method caused by debugger

Whilst debugging jsonrpclib with PyCharm I observed odd behaviour with jsonrpc._Method due to pycharm using the __repr__, __str__ and __dir__ methods in order to populate its debug information. These calls would be handled by __getattr__ which would modify the object, corrupting the method name chain. xmlrpclib does not have this issue because it does not make the same optimisation of mutating the existing object but returns a new object when __getattr__ is called (this might actually be a preferable approach to what i am proposing, so consider it as another option).

Let me know if there are any questions or concerns.