- The adaptive multiple time stepping integrator introduces separate time steps for space
      charge and "basic" external field integration.
    - Two kind of simulations will profit from it:
          1) Space charge dominated scenarios, where the space charge forces vary greatly, e.g.
             gun simulations ("A aspect")
          2) Scenarios where space charge is not dominant, but has a visible effect. Lowering
             of solver frequency can save considerable amaount of time while staying close to
             solution with full solve frequency ("MTS aspect")
    - First basic version, not yet tested well
    - Currently works only for single node and single bin
    - Details how to use it will follow