Too strict dimension and stride checking

[bluss]

It rejects some arr2 calls that are used throughout tests, for example

• arr2::<f32, _>(&[[], [], [], []]); (tests/array.rs ~350)
• arr2(&[[1.], [3.]]) fails dim_stride_overlap. (dim=[2, 1], strides=[1, 1], len=2)
• arr2::<f32, _>(&[[]]) also fails (tests/array.rs ~230)