Fix for ihooks.py breakage in Python 2.6

It looks like this bug has bitten a few people. Sorry for that. In a
perfect world, whoever implemented absolute imports should have
fixed the ihooks module as well. Oh well.

I think I've managed to fix it. I've posted a patch on the issue
tracker: <http://bugs.python.org/issue4152>. If some people could
test and provide feedback it would probably help ensure this gets
fixed in Python 2.7.

For those who want to use Python 2.6, a quick solution would be to
drop the updated ihooks module in the quixote/ptl directory.  You
can download it from: <http://python.ca/nas/tmp/ihooks.py>.