Oops.  The code for BTrees-based indexing was done on a branch, which
was later merged into another branch, which was later merged to the
trunk.  Somewhere along the way the change that actually enabled the
new index was lost.

Almost entirely concerned with adding ZPL blocks.

The timeout is necessary because in some cases a non-blocking connect
while neither succeed nor fail.  It is unacceptable to simply get
stuck forever in this code, because it is run at least once inside the
ClientStorage constructor.

Set the first timeout to a fairly low number -- 5 seconds -- so that a
ClientStorage(wait=0) call does not take a inordinate length of time.
Then set the default to a longer number -- 75 seconds, which is
typical timeout for a blocking connect() call.

This change fixes the hang in testZEOStorage from testStorageConfig.

XXX Need to get Guido to review the changes.

checkin.

really not reusable, so should be considered an implementation
detail.

- Define exceptions in the "Exceptions" module.
- Expose all the exceptions in the ZConfig package directly.

the end of the \modulesynopsis blurbs.

only used once within the ZConfig package.

exception specific to ZConfig is a specialization of
ConfigurationError.

by '$' or a name, raise an exception.  (Previously this used '' for
the replacement text.)

refactoring.

useful now that %define and substitution is built into the basic handling
of the configuration files.

Further documentation is needed.

Log message on platforms where file-locking isn't supported.

adding Dumper class to ZODB4.

Use 0/1 instead of True/False, since none of the other code uses
True/False.

There are few differences between the two files, except for necessary
differences because of API changes.  This change involves backporting
the new UndoError style from ZODB4.

- Update signature for the Context.parse() method
- Fix some broken markup

And whitespace normalization.