The Standby-branch was branched from the StandaloneZODB-1_0-branch,
which includes the BTrees-fsIndex code.  I didn't include that change
in the merge, but everything else.  Terse summary follows:

BaseStorage.py:
    Add read-only storage feature.
    Add TransactionRecord and DataRecord marker classes for iteration.
    Reformat some lines.

FileStorage.py:
    Add read-only storage feature.
    Greg Ward's ConflictError patch
    Reformat some lines.
    Add lastTransaction(), lastSerialno().
    Add bounds support to iterator().
    Use TransactionRecord and DataRecord.

Connection.py:
DemoStorage.py:
MappingStorage.py:
    Greg Ward's ConflictError patch

POSException.py:
    Greg Ward's ConflictError patch
    Add ReadOnlyError.