[boost] simplex method of Nelder and Mead

I uploaded code for nonlinear optimization via simplex method of Nelder and Mead, to files/simplex section. The origin of this code is somewhat unclear. I wrote this particular version using tx-math as a basis - however the tx-math code is clearly copied from numerical recipes in C. I think the present implementation is sufficiently different from the predecessors - however, I'm not a lawyer.