Investigate correctness of reshapes

[Ivorforce]

I just understood that reshapes can't always be views. I think xtensor should reject if reshape views if incompatible, but that doesn't seem to be the case:

	var array1 := nd.ones([10, 10], nd.Int8)
	print(nd.reshape(array1.get(nd.range(1, -1), nd.range(1, -1)), -1).shape())

(This should fail, but it doesn't, so what does it return?)

I think mostly nd.median might be at risk. But, we finally can use flatten() and reshape afterwards to fix it!