Make the local tests use "normal" unittest conventions.

Tim pointed out that loadEx is supposed to return a 3-tuple.  This is related to collector 1828 which was already marked as resolved.

The caller can't deal with using current data from loadBefore, so having an "end_tid" of None is useless.

Allow tempstorage to participate in MVCC.  Also fix minor bug where conflict cache could be poisoned by a transaction that failed after store was called.

      - Collector #1655: fixed severe memory leak in TemporaryStorage

  - replaced old CVS expansion with a clean $Id$
  - set the svn:keywords property to "Id"

When you check-in files in the future and want $Id$ to be expanded,
make sure it reads "$Id$" in that file; then set svn:keywords to "Id".

ZODB, ZEO, Persistence and similar packages were not modified since they
are really maintained elsewhere. Right now, we use a copy of them in our
Zope/Zope3 trees. We should go back to the module sharing (using
svn:externals).

connection can be holding on to an object with references to an object
that has been recently garbage collected.  When the object is unghosted in
the reference-holding thread, the storage cannot find the oid (because it's
out of storage due to gc).  We work around this by turning KeyErrors that
we believe are due to this scenario into ConflictErrors.