Go not through `__getitem__` for internal attributes (starting with `_`) in `Morphology.__getattr__`. Avoids an infinite recursion in Python3.
Allow any kind of number (not only integers) for the record argument in `StateMonitor` (will be converted to `int32`). In Python3, a simple expression such as `N/2` is a float, not an int.
Use explicit integer division (for Python3)