--restore-dir functionality

[zertrin]

Implement possibility to restore a directory to a specific directory.
For example, restore /var/www to /tmp

[zertrin]

Apparently this is already possible through the following equivalent command:

duplicity-backup --config /path/to/duplicity-backup.conf --restore-file rel/path/startdir /target/restorepath

@vwal has proposed the following solution:

It seems then that the functionality for “--restore-dir” is already there, and it can, perhaps, be added as an alias to “--restore-file”). Suppose “--restore-file” could alternatively be renamed to “--restore-file-or-dir”, but that might break cron jobs and scripts that rely on the existing arguments.

I'll follow his advice asap by adding the --restore-dir alias, document it and remove this item from the todo-list.

For more details see @vwal's comments here: http://zertrin.org/projects/duplicity-backup/#comment-1009

[zertrin]

Done with commits 03ef054 and 54f9aaf