Remove floor, ceiling for integer symbols

Original Intent

Allow optimizations by SymPy when we know that a TypedSymbol is_integer or is_real (e.g. drop rounding functions).

We can deduce some of those properties with Numpy's type system (https://docs.scipy.org/doc/numpy-1.13.0/reference/arrays.scalars.html). We have to be careful since all the is_* methods have ternary logic (True, False, None== we don't know).

Field.Access can take advantage of those optimizations by making it a subclass of TypedSymbol.

Extended Changes

By writing a test I realized that it would be handy to compare AssignmentCollections and use the functions find, match, subs, replace of SymPy.

pystencils/simp/assignment_collection.py

@@ -385,6 +385,9 @@ class AssignmentCollection:
             subexpressions=[a.replace(*args, **kwargs) for a in self.subexpressions]
         )
 
+    def __eq__(self, other):
+        return set(self.all_assignments) == set(other.all_assignments)
+
 
 class SymbolGen:
     """Default symbol generator producing number symbols ζ_0, ζ_1, ..."""