Change the debug variable to allow better control by the caller over how

debug output is managed.  The user can continue to use the current method
of passing a formatting string to have a replacement done and output will
be sent to the standard output exactly as it did before.  In addition they
can set it to a file object, sys.stderr for example, and the query string
will be printed to it.  Thay can also set it to a method (function) and the
query string will be passed to that method giving them the maximum flexibility
to do whatever they want with the query string.

I will be working with the PyGreSQL documentation shortly and at that time
will properly document this feature.