Spine editor already has:
(1) stepped, linear and a standard ease-in-out
(2) the ability to store your custom curves as presets, in case you need to reuse a curve you made over and over.
Just my opinion:
(1) I don't think these are 10 common eases. I think these are closer to some standards: http://easings.net/
But I have to say that some of them are too similar to each other or to a linear interpolation in terms of actual motion, so I generally think half of them are redundant. Others are just plain useless and tasteless. (who the hell uses EaseInBounce and EaseInElastic for anything other than a high school powerpoint presentation?)
(2) I'd be all for ease functions it meant they're more performant. I think a third of the time, I really only need an EaseOutExpo curve. The other third is an ease-in-out. Otherwise, I guess it'd be nice to have more presets built-in for new users.
(3) In-editor reference, I think it would be neat, but generally only useful to beginners. After a few days, you get what the curves do, and their actual behavior actually changes based on how long the interpolation is.
(4) It would be cool for the site though. I think this topic in general is worth adding to the list of nice docs/infoblogpostthing to make. So... coming soon, I guess!
