python - pq: Move (tracenull)RaiseTransactionError to

Log Message:
-----------
Move (tracenull)RaiseTransactionError to (Transaction)exc_info.

Move the contents to of the RaiseTransactionError function in Proboscis to the
exc_info method on the client3.Transaction class. This is a more appropriate
location for this as it allows any PQueue implementation to use the
functionality.
(Some attribute renaming ensued. Primarily _exc_info and _nf_exc_info.)

Modified Files:
--------------
pq/src:
client3.py (r1.17 -> r1.18)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/pq/src/client3.py.diff?r1=1.17&r2=1.18)
transam.py (r1.7 -> r1.8)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/pq/src/transam.py.diff?r1=1.7&r2=1.8)
pq/test:
client3.py (r1.8 -> r1.9)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/pq/test/client3.py.diff?r1=1.8&r2=1.9)