Add `IMG` Zsh globbing helper function
Add `IMG` Zsh globbing helper function

Filters a glob by whether its `file --mime-type` starts with `image/`.
Example usage:

    mv ~/Downloads/*(+IMG) ~/Photos/

benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles,benizi/dotfiles