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

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.