chain for its transient object container.

Changed session data manager to splice itself into the transient
object container's acquisition path before returning a session
data object via getSessionData.

Updated unit tests to reflect changes.

returning X, contradicting the docs and common sense.
difference(None, X) continues to return None.

- removed obsolete code trying to deal with a trailing 'L' for longs

Changes:

 - More stable under high usage, especially in the face of
   situations under which there are many ZODB conflict
   errors. The previous implementation had stability problems
   when many conflict errors were encountered; especially
   conflicts that were generated as a result of a simultaneous
   change to a subobject of the TOC (such as in the case of a Zope
   application which makes heavy use of both frames and
   sessions).

 - More conflict-resistant.  Instead of ignoring the likelihood
   that multiple threads will attempt to perform the same actions
   simultaneously in methods of the TOC (which often causes
   conflicts), the new implementation attempts to avoid conflicts
   by employing a chance-based housekeeping model.  In this model,
   one thread is "elected" by chance to do the kinds of tasks that
   cause the most conflicts.

 - Now uses a "timeslice" based model instead of a "ring" based
   model.  This also helps cut down on conflicts and makes
   the code slighly less obfuscated (not much, though! ;-)

 - Quite a few more comments in the code.

 - Changes to the sessioning stresstest (which exposed the
   bug that made me reimplement the TOC in the first place).

 - Updates to unit tests.

 - A "HowTransienceWorks.stx" document which attempts to
   explain how the code works.  It's not stellar, but
   it's a start.

 - Changes to the TransientObject class that the TOC
   hands out (typically as a "session data object"), in order
   to make invalidation less Rube-Goldberg-ish.

The structure of the TOC object has changed enough that in order to
maintain b/w compatibility, an in-place upgrade of "old" instances
is implied by running them with this code.   "Upgraded" instances
are not backwards-incompatible, however, so folks can hopefully
move back and forth between Zope versions without much hassle.

and unused definition of _marker

printed properly

installed when using medusa directly (e.g. monitor_client).

Rather than trying to deal with the portability issues, just use
sprintf() with suitability limits on the strings.

It's experimental because I just called snprintf() directly, even
though later version of Python go through elaborate rituals before
calling it.

caused trouble with backward compatiblity. The content of the __init__.py is
necessary for pre-2.6 installation but no longer used in 2.6.

better performance for higher end machines (that are more likely to be in
use in production systems).

Caused the meta-signal-handler method to log when a registered handler fails.  Also fixed a bug in logfile rotation.

A couple of documentation and formatting cleanups.

Warn if users are using Python 2.1.X where X < 3.

Warn if users are using Python 2.2.

importance of cache size and the need to recompile extensions for
PER_GHOSTIFY().

Add entries for the Connection change made today and a very generic
entry to describe all the BTrees bugs that Tim has fixed.

encoding with cache servers.