- add name here to be inserted in the argument
- Added :attr:`alembic.config.Config.cmd_opts` attribute,
allows access to the `argparse` options passed to the
`alembic` runner.

- Added new command line argument ``-x``, allows extra arguments
to be appended to the command line which can be consumed
within an ``env.py`` script by looking at
``context.config.cmd_opts.x``.