Extensions and fixes to the type system

• Fix hashing and equality checks of TypeAtoms
• Fix natural alignment in struct types
• Allow to manually specify data types for shape and stride symbols
• Add "half"/"float16" to the type parser
• Add a DynamicType front-end class for CastFunc to decide the cast target during kernel translation; might find additional applications for this in the future

src/pystencils/sympyextensions/typed_sympy.py

@@ -247,7+247,7 @@
         #
         # lhs = bitwise_and(a, cast_func(1, 'int'))
         # rhs = cast_func(0, 'int')
         # print( sp.Ne(lhs, rhs) ) # would give true if all cast_funcs are booleans
         # -> thus a separate class boolean_cast_func is introduced
         if isinstance(expr, sp.logic.boolalg.Boolean) and (
             not isinstance(expr, TypedSymbol) or isinstance(expr.dtype, PsBoolType)
@@ -278,7+278,7 @@
 
     @property
     def is_integer(self):
-        if isinstance(self.dtype, PsNumericType) or self.dtype == DynamicType.INDEX_TYPE:
+        if self.dtype == DynamicType.INDEX_TYPE:
+            return True
+        elif isinstance(self.dtype, PsNumericType):
             return self.dtype.is_int() or super().is_integer
         else:
             return super().is_integer