Nox: Least squares solver

Created by: qichenghua

Nox::Lapack::LinearSolver: In case the jacobian is singular in Newton's method (or more generally, in line searches which used Newton's direction as search direction), lu decomposition failed and returned the right hand side as search direction (if the parameter "Rescue Bad Newton Solver" was set to true). We enhanced this by taking the linear least squares solution as search direction p, which solves DF(x)p=-F(x) (where F(x)=0 is the nonlinear equation system of interest) if this linear system has solutions. We believe that this is more sophisticated than just taking the vector p=-F(x).