Add New Default Avatar [Emrikol's Fork] free WordPress plugin

I’d been manually adding custom default avatars in functions.php for a while, and it was always a hassle to edit it to change them. I decided to see if there was a plugin available to do the job, and stumbled upon “Add New Default Avatar” here: https://wordpress.org/extend/plugins/add-new-default-avatar/ It was nice, but it was missing some features such as the ability to manage avatars, upload images, and automatically resize thumbnails. So I made a few modifications