- Avoid more than one round-trip call when loading blobs via copy from
  the server.

- Avoid loading large amounts of blob data into memory.  The old
  storeBlob implementation was likely to queue blob adta faster than
  it could be sent, leading to a large memory foot print for the
  queue. Now, iterators are used to read data from files only when the
  network layer is ready to send it.

- Fixed storeBlob to move the input file to the blob cache (when not
  sharing the blob directiry with the server).

- Extended the loadBlob locking model to work with multiple processes
  by using file locks rather than threading locks.  A common
  configuration is to use a client process per core, so that a machine
  is likely to have many client processes and it should be possible
  for the client processes to share a common blob cache.

Now it also truly consumes files.

Binary mode is implicit.

all OS files in binary mode.  Binary mode for blobs is now implicit.

Added a temporaryDirectory method for getting a directory to use for
creating temporary files.

temporary directory to work around current blob limitations that blob
files and storage blob directories need to be on the same device.

use an iterator to send a large file without loading it in memory.

Updated the ZEO protocol to reflect the new Blob-support methods.

use an iterator to send a large file without loading it in memory.

- Found and added a test for a race condition arising from creating
  and removing lock files.

- Change to leave lock files behind.

- Use the windows locking implementation from msvcrt from the standard
  library, rather than using a custom extension module.

to die when removing test directories.

to give time for servers to stop, since windows won't let us remove
files or directories if they are in use.

Windows when Blobs aren't used.

Fixed a typo.

generate it's own invalidations.  Also updated to honor the storage
APIs more carefully.  These changes together allow a ClientStorage to
be served by a storage server.

queued.

return values.

storage server.

Removed subtransaction support.

isolation between connections, rather than using the no-longer
supported synch=False hack.

simplify the code a little. (We'll be able to simplify more when we
stop supporting versions.)

Suppress version-deprecation warnings for tests.

Added deprecation warnings for using versions.

unpicklable, so implement pickle support directly (with tests)

Removed unused supportsTransactionalUndo.

Simplified and fixed a bug in getTid.  Now handles undo of object
creation.

Added note that record_iternext doesn't work with versions.

storages that don't support versions or that don't support undo.

Changed some comments to doc strings.

Deprecated storages without tpc_vote.

Removed the modifiedInVersion cache.

Added an XXX about the broken ResourceManager implementations.

loadEx isn't a storage method.

loadEx helper function from VersionStorage, since loadEx isn't a
storage method.