wp-cli/wp-cli — pull request #323 by jmslbam (2013-02-25 16:59:28+00:00)
Title: Media command regenerate all of one by ID

First part of the media command as spoken in #88
Scribu mentions @benmay ported the coded from @Viper007Bond to wp-cli.
Took the time to integrate the whole thing.

`wp media regenerate --id=xx` regenerates only that image
`wp media regenerate` default regenerates all images.

Should there be a extra param `--all` to explicity start the regenrating and add a check like

`if ( !$id && !$all)

ext(1);