added test script and expected output file as well
this closes patch 103297.
__all__ attributes will be added to other modules without first submitting
a patch, just adding the necessary line to the test script to verify
more-or-less correct implementation.
be more intelligent when the database already exists (use the module
for the existing file, according to whichdb). Noted in the doc
strings that there doesn't seem to be a different between 'c' and 'n'.
pickle.py: new low-level persistency module (used to be called flatten)
dbmac.py: stupid dbm clone for the Mac
anydbm.py: generic dbm interface (should be extended to support gdbm)
