ClientStorage could be in either "sync" mode or "async" mode.  Now
there is just "async" mode.  There is now a dedicicated asyncore main
loop dedicated to ZEO clients.

This addresses a test failure on Mac OS X,
http://www.zope.org/Collectors/Zope3-dev/650, that I believe was due
to a bug in sync mode. Some asyncore-based code was being called from
multiple threads that didn't expect to be.

Converting to always-async mode revealed some bugs that weren't caught
before because the tests ran in sync mode.  These problems could
explain some problems we've seen at times with clients taking a long
time to reconnect after a disconnect.

Added a partial heart beat to try to detect lost connections that
aren't otherwise caught,
http://mail.zope.org/pipermail/zodb-dev/2005-June/008951.html, by
perioidically writing to all connections during periods of inactivity.

o Most notably, ZEO.ClientStorage (http://www.zope.org/Collectors/Zope/2016).

o Forward-ported from 3.4 branch.

I'm not particularly proud of the tests I wrote.  It's way to hard to
write tests for ZEO.  Without a lot of white-box trickery, nothing can
be tested without making network connections, which is insane. ZEO's 
architecture needs to change.

I finally had to resort to os._exit, which I'm not happy about,
although I don't suppose it could do any harm for the test runner.

I wonder is a test is leaving something behind it shouldn't.

Also return the test result status as the exit status.

PersistentMapping was inadvertently pickling volatile attributes (http://www.zope.org/Collectors/Zope/2052).

See http://www.zope.org/Collectors/Zope/2027.

replaced `x` with repr(x), and replaced apply(x, y) with x(*y)

For multiple undo to succeed, the undo operations have to be
performed in a specific order.  The order was not being retained
by ZODB and was instead semi-random (the order depended on the
id() function.)  Now undo operations (as well as all
ResourceManagers) are sorted by creation order.

in the second iteration

ZODB uses `buildsupport` now, not `zpkgsetup`.
Updating this info in PACKAGE.cfg is needed to
build a release tarball.

_ConnectionPool._reduce_size():  when forgetting a Connection
due to exceeding pool_size available connections, clear its
cache right away.  Because such a connection can never be in
the open state again, hanging on to resources in its cache is
just wasteful.  This was reported as "a problem" on zodb-dev
recently, although it's unclear how the poster got into a state
where it mattered so much.

New zdaemon.

_setstate():  An MVCC optimization was inadvertently disabled by
fixes for ZClasses.  Repaired.

Elsewhere, repaired English in comments.

NEWS.txt:  removed news from 3.6 and earlier.

Dmitry seems to have vanished :-(

Note that nailing the type of oid to str may allow some
thread simplifications in Connection._invalidated handling.
Thanks to Florent Guillaume for noticing!

  tools need to perform minimal logging configuration themselves. Changed
  the zeoup script to do so and thus enable it to emit error messages.

http://mail.zope.org/pipermail/zodb-dev/2005-March/008593.html

with zope.whatever librairies that might be installed on the Python
version used to launch these tests.

- no longer try to find pop and popitem on UserDict as all supported
  Python versions have them
- added a test for the default argument of pop()
- added a NEWS.txt entry about pop()

- added unit tests for persistend mapping

Testing from a checkout is different than testing from a
distribution now.  Explain the differences.  Removed the
business about fiddling PYTHONPATH, because it shouldn't
be needed (and isn't for me ;-)).

same file as ZODB/tests/testConnectionSavepoint.txt. Do we really need 
both?

some good documentation here; I added all those files as chapters to the 
Zope 3 apidoc.