New organization for Optim+family

I hope the Base package makes the API non-package specific. There are some good nonlinear solvers outside of this crew (Kinsol from Sundials is one, Roots.jl is another). It would be great for library code to finally have swap-ability between them, a la

Do you have an idea for what this API is going to be looking like? We can talk more in the chats if it’s still at an idea stage and don’t want to set anything in stone, but I know you’ve been working on it for a bit so maybe there’s already a proposal somewhere?