WIP: Graph datahandling

This is the draft for a data handling that (optionally) forwards all calls to SerialDatahandling. All calls and data transfers get recorded for the creation of an execution graph.

Needs to be changed after the breaking changes in datahandling.

Needs a tiny change in lbmpy:

Instead of using TimeLoop(...) for time loop creation a custom function is used.

pystencils/kernelcreation.py

@@ -76,6 +76,9 @@ def create_kernel(assignments,
                [0., 4., 4., 4., 0.],
                [0., 0., 0., 0., 0.]])
     """
+    #save the original assignments
+    assign = assignments
+    
     # ----  Normalizing parameters
     split_groups = ()
     if isinstance(assignments, AssignmentCollection):
@@ -130,7 +133,8 @@ def create_kernel(assignments,
     if use_auto_for_assignments:
         for a in ast.atoms(SympyAssignment):
             a.use_auto = True
-    ast.assignments = assignments
+    ast.assignments = assign
+    ast.indexFields = False
 
     return ast
 
@@ -181,6 +185,9 @@ def create_indexed_kernel(assignments,
                [0. , 0. , 0. , 4.3, 0. ],
                [0. , 0. , 0. , 0. , 0. ]])
     """
+    assign = assignments
+    indF = index_fields
+    
     if isinstance(assignments, Assignment):
         assignments = [assignments]
     elif isinstance(assignments, AssignmentCollection):
@@ -213,7 +220,8 @@ def create_indexed_kernel(assignments,
     else:
         raise ValueError("Unknown target %s. Has to be either 'cpu' or 'gpu'" % (target,))
 
-    ast.assignments = assignments
+    ast.assignments = assign
+    ast.indexFields = indF
     return ast