Image index ordering in Python API

[dzenanz (Dženan Zukić)]

@matt.mccormick

attribute access, e.g. image.spacing, image.size, image.shape is NumPy/scikit-image index order, function access, e.g. image.GetSpacing() is ITK/Nibabel/VTK index order.

My primary language is C++, not Python, so my opinion might not be widely shared. But this sounds like it would create more confusion than it would solve.