[Feature Request] Serde derive support, for saving state in eframe

[dRAT3]

Eframe uses serde to save state, but it isn't implemented. Since it is a quite easy task I can take it of your hands if you'd like. I'm going to do it any way in my fork

[ryo33]

@dRAT3 Seems nice! It could be good to have a cargo feature but it’s not required to merge it. Thanks.