- Equilibrium class did not do "+1" density shift correctly
- support for generating single precision models

- separate lbmpy module
- code generation for walberla
- isolated code to generate a listlbm update rule from collision rule

- test run again
- notebooks not yet

- assignment collection
- sympyextensions

- Previously sympy.Eq was used to represent assignments. However Eq
  represents equality not assignment. This means that sometimes sympy
  "simplified" an equation like a = a  to True,
-> replaced sp.Eq by pystencils.Assignment everywhere
- renamed EquationCollection to AssignmentCollection

- notebooks are considered in coverage analysis now
   -> custom notebook runner plugin adapted
- added images for documentation

- splitted existing LBM boundary handling into two parts:
    -> generic part , that is used for FD as well and moved it to pystencils
    -> LBM specific part - remained in lbmpy

- bugfixes

- now an lbMethod or updateRule can be passed in directly
- made method/update rule/ast function independent i.e. no function
  uses the same parameters as on of the others

- 3 phase model works now with step sytem

- scaling interface width eta instead of surface tensions tau to correct
  interface profile & surface tensions

- added rudimentary test to prevent these kind of problems

- renaming because of clashes with types.py from other packages

- fieldLayout parameter default was not really used
- switched default field layout for sweeps that are generated for
  waLBerla, from a C to a Fortran layout (i.e. loops are ordered
  z,y,x from outer to inner, to match waLBerla fields)

- support for kernels that run over walberla ghost layers

- works for 2D models now as well
- moved lattice boltzmann code generation to lbmpy_walberla module