csv, db, or spreadsheet export

[krzentner]

I advertise doexp as being equivalent to maintaining a spreadsheet of experiments, but it doesn't actually have the option to synchronize with a spreadsheet. There's currently the --dry-run flag, which prints out all commands to be run, but no way of exporting what commands doexp thinks are running, done, ready, or waiting on inputs.

This should be fairly easy to implement, and would help with keeping track of what experiments are running.