Remove optimize & bug fix

• io: Adjustment so that hdf5 tracks the order of dicts.

• simulations:

  • Adjust printing: correct simulation results for adjusted solver printing
    levels; default solver verbosity is new 1; log can now be
    overwritten in solver_opts (mainly for debugging).

  • Functions moved out of simulations: expand_grid_model moved to
    models and estimate_gridding_options to meshes. The
    availability of these functions through simulations will be removed in
    v1.4.0.

• optimize: the module is deprecated and will be removed in v1.4.0. The two
  functions optimize.{misfit;gradient} are embedded directly in
  Simulation.{misfit;gradient}.