- support for kernels that run over walberla ghost layers

- old method produced unused variables
- old method was not deterministic in the output code i.e. ordering of
  the introduced constants
- moveConstantsBeforeLoops transformation was also not deterministic

- lbmpy plotting uses the pystencils plotting now

-> reading from arrays was slower with some compilers

- generates a lattice model and a sweep
- support for refinement parameter scaling

- pystencils can create now a non-compilable kernel that can be
  analyzed by kerncraft

- helps when simulating a large amount of small scenarios

- periodic kernels not yet OpenMP parallel