dat backup - save current version to local history storage

Add dat keep command and/or --keep option to store the history in a local clone, started in this branch.

The goal would be to have a local copy of history that:

1. Works offline
2. Can act as a permanent or temporary backup of history
3. Store separately from dat files

Usage:

• dat share - imports files
• dat keep - saves current archive version and files to ~/.dat/history/<discKey> as sleep files (i.e. with content.data).

Or

• dat sync --keep - live import + keep all history

Feel like it’d be good to have a way to:

1. list what archive versions we have locally
2. clear local cache of all/specific versions
3. clear local cache compared to a remote copy (e.g. clear everything locally that your server has backed up)

[bnewbold]

I’d still love to see this! Or at least flags to dat init (CLI) which ensures all future added/synced data is saved, and a flag to dat clone that both pulls full history and “checks out” the latest versions to the current folder. I know hypercored has some of this functionality, but I think it’s basic enough that it should be possible with dat itself.

[joehand]

Started updating https://github.com/joehand/dat-backup/tree/new-api