zodbrestore - Tool to restore content of a ZODB database from zodbdump output

Zodbrestore is long-coming counterpart to zodbdump. Implementation is internally based on reworked zodbcommit.

For FileStorage restored database is verified via test to be bit-to-bit identical to the original.

For NEO it won't be exactly the case, as NEO does not implement IStorageRestoreable: there is only tpc_begin(tid=...) but no restore().

Please see individual commit messages for details.

/cc @jerome, @kazuhiko, @vpelletier, @jm, @arnau