WP SMUSH adding on the fly image resizing

Hi all

I would like to suggest adding on the fly image processing to WP SMUSH to make it even more powerful.

Right now lots of images get stored in a WordPress installation. Just checked my small site and it already smushed over 17.000 images and isn't finished, probably because it is creating multiple of sizes which afterward not even get used or are not demanded at all.

Therefore the resizing part should actually not be done by default but instead only and really ONLY if it gets also requested.

https://wordpress.org/plugins/resizefly/

There are several plugins doing that and one which is doing it pretty well and is also on GitHub would be resizefly
https://github.com/alpipego/resizefly/

I would like to suggest to add it to work together with WP-SMUSH or even better to integrate that functionality into it beside also adding a way to delete actually all generated images which are no more used at all.

Thanks
Andi