Reviewed by Nick Coghlan.

be compatible with Python 3.0, also.

  http://www.jcea.es/programacion/pybsddb.htm#bsddb3-4.7.3

This patch publishes the work done until now
for Python 3.0 compatibility. Still a lot
to be done.

When possible, we use 3.0 features in Python 2.6,
easing development and testing, and exposing internal
changes to a wider audience, for better test coverage.

Some mode details:
http://www.jcea.es/programacion/pybsddb.htm#bsddb3-4.7.2

object available as bsddb.db.api.  This is based on the patch submitted
by Duncan Grisby here:
  http://sourceforge.net/tracker/index.php?func=detail&aid=1551895&group_id=13900&atid=313900
See this thread for additional info:
  http://sourceforge.net/mailarchive/forum.php?thread_name=E1GAVDK-0002rk-Iw%40apasphere.com&forum_name=pybsddb-users

It also cleans up the code a little by removing some ifdef/endifs for
python prior to 2.1 and for unsupported Berkeley DB <= 3.2.