staying under 5000 bytes.  There appears to be a race in the test.  If
the cleanup thread is slow enough, it will prevent later cleanup
threads from running. Need to think about this.

collection, http://wiki.zope.org/ZODB/ExternalGC, has been defined
and implemented for FileStorage.

initial data as a string argument to the Blob constructor.

blob-sie-check percent.

tpc_finish doesn't specify a return value and having one makes tests
messier.

file storages.

Also fixed a bug in handling the create option with blob support.

efficient packing (and undo).

ignored when doing GC.  That is, when traversing from the root, if a
reference object wasn't found, it was simply ignored, covering up a
potential problem.  Now raise a key error, which stops packing.

return an object count of 0.

that.

tests more precise to aid test debugging.

Changed the default blob-cache-size-check size to 10%.

Changed the algorithm for deciding the target for blob cache
reduction. Now the target is

blob-cache-size * (100 - blob-cache-size-check)/100

testing a storage. :)

Made it possible to opt out of recovery tests.

blob-storage implementations.

independent.

use "import time" so we can mess with time.time in tests.

non-shared blob directories, you can set a target cache size and the
cache will periodically be reduced to the target size.

To enable blob cache management, a new IBlobStorage method,
openCommittedBlobFile has been added.

defeat FileStorage's index optimization.

data for reading as an ordinary file, rather than as a blob file.
The ordinary file may be used outside the current transaction and
even after the blob's database connection has been closed.