Ported from ZODB3-3_1-branch.

The ZEO client cache now works with OIDs of length up to 65535 bytes.
Also added some sanity checks that check the size of the data being written,
since there are some hard limits.

ZODB now makes no assumptions about the length of OIDs (although
storages can make such assumptions if they need to.)  Added an
oid_repr utility function to print both 8-byte OIDs and other OIDs in
a reasonable way.

ones.

which makes it impossible for teardown to delete the file on Windows,
which causes this test to fail, and also "the next" test to fail because
its setup can't delete Source.fs either.  So explictly close the storage
iterator.

After the merge, I made several Python 2.1 compatibility changes for
the auth code.

transactions on both sides of it.  The coarse granularity of time.time()
on Windows causes this test to fail sporadically otherwise.

MappingStorage (it doesn't support undo).

Remove comments out test.

Disable test for ZEO + MappingStorage, since it doesn't support undo.

storing a 128K transaction note and it shouldn't cause this test to
fail.

Disabling the test by commenting it out.

New tests covering corner cases in the storage API, derived from code coverage analysis of DirectoryStorage. FileStorage currently fails checkCreationUndoneGetSerial

Check whether a registered extension method already exists before creating the marshaller attribute. This allows for a smooth migration should a former extension method be promoted to the normal storage interface.

Remove signals file, since the only signal you actually need to use is
for log-file rotation.

A few changes to the rST formatting.