Added command file and skeleton for methods
Merged code from @benmay, would have liked to merge his commit but time aint on my side
Cleaned up error
Added the regenerate --id=
Removed unused coded and the bla
Cleanup before pull request and add props to Viperbond007
Added confirmation check before regenerating all images
Skip confirmation if `id` arg is given
First start better naming
Adds scaffolding for child theme (based on Twenty Twelve by default)

Apart from creating an empty underscore theme, it would be cool to be
able to create an empty child theme. I've implemented a very basic
command for this. It created a theme folder and style.css which imports
parent theme's styles
Optimizing looping and unlinking of the resized images
Removed use of $error
Removed settings timeout
Use concate instead of sprintf
Using WP_CLI::warning
Using WP_CLI::warning
Polished some feedback messages
Cleaned up unused code
Better grammar
Fixed variable name so thumbnails get unlinked again