Introduce stacked curves view

simply put, curves view is incredibly important for any modern animator, but the current implementation forces the user to either view all the curves at once, which is often messy, or go through the process of turning other curves off and on, to find the one they want (all the Y axis curves are green. that means each bone in a rig will have up to 3 similar curves, and a rig may end up with 30 or so animated green curves, for example.)

in normalized view, a curve that goes between 1 and 100 would share the same height and space as one that goes from 0 to .01 . While intended, overlaying the two scales into the same physical space causes a certain amount of cognitive dissonance, and doesn't play nice when scaling curves to tune an animation

My proposal is to introduce a "stacked curves" mode, alongside normalized mode. something like this; you can probably already see the use- it basically eliminates the issue of grabbing keyframes that are just about overlapping, along with overlapping tangent handles, and clears up a lot of visual clutter. As well, any curve that is normalized can more easily be understood to have its own scale independent of others. I imagine the button to enable it would go beside normalizing. you'd usually want them together anyway, and they're both curve display variations.