Updated testing of kerncraft_coupling and some functions in
kerncraft_coupling in order to be compatible with the kerncraft version 5.1

Testcases test_mu_equivalence, test_phi_equivalence are passing.

- support for logical operators, and/or
- both phase field kernels can be vectorized now

- phasefield phi sweep vectorizes successfully

Fixed a severe bug. Renamed makePythonFunction of the llvm backend.
Deleted code duplicity.

Fixed function bug.

Added LLVM: CodePrinter and a compiler
Updated data_types
Added tests
Added jupyter notebooks
Fixed bugs
Restructured transformation functions

- activated vectorization for LBM kernels

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

- sympys piecewise defined functions are mapped to blend instructions
- cast function is now a class
- several bugfixes

- first vectorization tests are running
- type system: use memoized getTypeOfExpression
- casts are done using sp.Function('cast')
- C backend adapted for vectorization support
- AST nodes can required optional headers

- 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