CreateArray now outputs `IntN` and `FloatN` type arrays (when possible)
There wasn't a way to safely downcast to IntN and FloatN type arrays (vtkTypeInt8Array for
instance) created by vtkAbtractArray::CreateArray(int dataType). Being able to downcast to such
arrays is especially important for readers, which only have a quantitative description of the
underlying type of the arrays to read: it knows if the arrays is storing a floating point number or
an integer, and its size per element. VTK defines arrays using this nomenclature,
which are set to inherit from a native-typed data array type counterpart
(vtkLongLongArray for instance) matching its element size.
IntN or FloatN arrays inherit from a native-typed data array share the same
data type. For instance, VTK_TYPE_INT64, the data type of
vtkTypeInt64Array, either equals VTK_LONG or VTK_LONG_LONG.
From now on, when calling vtkAbstractArray::CreateArray(int dataType), if dataType is
used by any IntN or FloatN array type, then an instance of this array is created, instead of its
native-typed data array counterpart. This means that it is now safe to do
vtkArrayDownCast<vtkTypeInt64>(vtkAbstractArray::CreateArray(VTK_TYPE_INT64)).
As a reminder, here is a list of new array types that can be created:
vtkTypeInt8ArrayvtkTypeUInt8ArrayvtkTypeInt16ArrayvtkTypeUInt16ArrayvtkTypeInt32ArrayvtkTypeUInt32ArrayvtkTypeInt64ArrayvtkTypeUInt64ArrayvtkTypeFloat32ArrayvtkTypeFloat64Array