Remove old code

[dpsanders]

Remove old code:

• bisection.jl

• move out definitions of N used in branch_and_prune

• krawczyk.jl

• newton.jl

• find_roots stuff

[Kolaru]

Is the code in newton1d.jl still considered maintained and part of the current API ?

[dpsanders]

That was added in last year's GSoC project.

In a way it's useful to have a separate code, but the actual code itself is long and convoluted. We should see if anything is salvagable and probably get rid of the rest.

cc @eeshan9815

[eeshan9815]

If I recall correctly, it worked well for complicated functions, and functions which had a lot of multiple roots, where the existing solver sometimes struggled. So, should it be implemented as a part of the roots interface and kept as a different keyword solver?