Improvements to state interpolation

[aaronsantiago]

I see a lot of discussion on this in various places in the repo, though a lot of it is a bit difficult to understand for me b/c of how deep into the software the discussion gets (along with some of it being in French...)
#439
https://github.com/orgs/ossia/projects/44?pane=issue&itemId=71086967&issue=ossia%7Cscore%7C581
https://github.com/orgs/ossia/projects/44/views/1?pane=issue&itemId=71086982&issue=ossia%7Cscore%7C659

etc.

The issue I'm seeing now is--it's wildly difficult to create curves for many addresses at once. For example:

1. Create a state

2. Create another state with different values (connected via interval)

3. Interpolate?

All of a sudden, I've created quite a difficult scenario. If I want to modify the curves, I have to be careful:

• The start and end values have to match the states that I've created, for each address. This could be MANY addresses potentially (imagine controlling a specific array of lights, or the position of a set of objects)
• Each curve must be manually set up in a way that matches the others
• I have to mentally keep track of which curves haven't been edited, and do so via a very specific menu (I know this is unrelated but this doesn't make sense to me)
  • 

All this just to set it up once--if I ever want to change the curve behavior it would get QUITE unwieldy.

An idea that I had that maybe makes sense within the philosophy of Ossia was to try controlling the playhead of a disconnected interval:

Given many such automations, this could get tedious. I'm not sure what the exact best way to do this would be, but my first thought is a process that does essentially exactly what I've done above but in a single window--and as the default action for "interpolate states". I believe this would create a massively improved artist experience when managing a mass of cues.