wx.lib.pubsub updates from Oliver Schoenborn:

wx.lib.pubsub updates from Oliver Schoenborn:
    - the hash problem re non-hashable objects
    - now supports listeners that use *args as an argument
      (listener(*args) was not passing the validity test)
    - corrected some mistakes in documentation
    - added some clarifications (hopefully useful for first time
      users)
    - changed the way singleton is implemented since old way prevented
      pydoc etc from extracting docs for Publisher

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38591 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775