Autocomplete for executable (not shell)

[davidmarkclements]

We have autocomplete in the shell via vorpal, however it would be great ux if we can have autocomplete the general executable, e.g. fuge generate or fuge shell

For os x and linux this would be meaning running source on a commands bash file (e.g. Like nvm does) - not sure how this would be achieved in windows. We could either have autocompletion as default or follow the npm autocomplete pattern