Merge branches 'mdw/pwsafe' and 'mdw/ec-ptcmpr'

* mdw/pwsafe:
  pwsafe: New command `xfer' to transfer data to a new database backend.
  catacomb/pwsafe.py: Add a backend based on SQLite.
  catacomb/pwsafe.py, pwsafe: Make GDBM support conditional.
  catacomb/pwsafe.py: New Git-friendly `DirectoryStorageBackend'.
  catacomb/pwsafe.py: New FlatFileStorageBackend class.
  catacomb/pwsafe.py: Add a new ABRUPTP argument to `close' methods.
  catacomb/pwsafe.py, pwsafe: Dispatching for multiple backends.
  catacomb/pwsafe.py: Split out the GDBM-specifics from StorageBackend.
  catacomb/pwsafe.py: Factor database handling out into a StorageBackend.
  catacomb/pwsafe.py: Commentary fix.
  pwsafe: Abolish the `chomp' function, and only chomp when reading stdin.
  catacomb/pwsafe.py: Make `PW' be a context manager, and use it.
  pwsafe: Get the master passphrase before the new password.
  pwsafe: Report password mismatch as an error, not an exception.
  pwsafe: Some simple reformatting.
  catacomb/pwsafe.py, pwsafe: Replace `PW''s MODE parameter with WRITEP flag.
  catacomb/pwsafe.py: Abolish the `PWIter' class.
  pwsafe: Eliminate the `dump' subcommand.
  pwsafe: Present the list of commands in alphabetical order.
  pwsafe: Don't produce a backtrace on decryption failure.

* mdw/ec-ptcmpr:
  catacomb.c, ec.c: Bindings for the new EC2OSP/OS2ECP functions.