Draft: Changes for compatibility with pystencils 2.0

Introduce a significant number of patches for compatibility with the upcoming pystencils 2.0.

Status:

• Fix field duplication in create_lb_update_rule: Remove the workaround once field duplication is fixed in pystencils
• Data types in boundary handling: LatticeBoltzmannBoundaryHandling does not allow to specify a data type and always uses float64. This leads to type errors when combined with LB fields with float32 dtype.
• Mixed precision: Need to explicitly insert casts at field reads/writes when computing and storing PDFs in different float formats

src/lbmpy/boundaries/boundaryhandling.py

@@ -178,7 +178,7 @@ def create_lattice_boltzmann_boundary_kernel(pdf_field, index_field, lb_method,
             **kernel_creation_args
         )
 
-        default_data_type = config.default_dtype
+        default_data_type = config.get_option("default_dtype")
 
         if force_vector is None:
             force_vector_type = np.dtype([(f"F_{i}", default_data_type.c_name) for i in range(dim)], align=True)