This is v0.4.3. Solvers done

This version includes the draft of Chapter 4: Fixed Point Problems and Anderson Acceleration

I have decided to take my own advice from the middle of the discussion in

https://discourse.julialang.org/t/quasi-newton-nonlinear-solver-for-sparse-jacobian/57672/8

and leave Broyden's method out. So, the solvers are done.

The last chapter will be Chapter 5: Case Studies.