System solution
Created by: aminevdom
SOD problem is solved by point_sort_shift solver and nn_autograd_optimizer.
- Input_preprocessing file: operator_prepare is changed, it determines what type of problem we have (1eqn or system)
- Solver file: print_solution_autograd is added as ordinary print_solution doesn't work with autograd solver. Plotting 3 graphs is added in print solution function (irrationally).
- Cache: variables number determination is changed for system term
- Metrics: point_sort_shift_loss is changed for system term and autograd method is fixed for system term too