Add a 'rename' command.

[Ovid]

We're looking at best practices for sqitch and we're considering ways of using subdirectories, such as:

sqitch add $table_name/add_column_foo

(Obviously, migrations spanning multiple tables might be handled differently).

Such a scheme would allow us to fairly easily see the history for a given table. However, we'd like to move our old migrations to the new structure. Currently this appears to involve updating events.change, changes.change, and dependencies.dependency in the sqitch database and all relevant entries sqitch.plan file. That's fraught with error and if the sqitch.plan format changes, or the database schema changes, any tools we build might break.

I would love to be able to do this:

sqitch rename $old_name $new_name

[theory]

I think you're going to want have something likesqitch rebase --force --log-only. That functionality is currently under discussion in #200.