python - typ: Make record more "subclassable".

Log Message:
-----------
Make record more "subclassable".

Introduce an 'atttypid' attribute that by default is set to "()" (empty tuple).
This is what the sender and receiver will use to specify or validate the typids
sent or received.

Modified Files:
--------------
typ/src:
root.py (r1.1.1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/typ/src/root.py.diff?r1=1.1.1.1&r2=1.2)