slice(): Rewrite to return view instead of copy

[mateogianolio]

Related

• Add strides #153

Notes

Following numpy's philosophy; it is more often more efficient to return a view of the data when slicing, transposing, etc. Slicing should return a view of the old data instead of allocating more memory.

This way, the following would be possible:

const x = v.array.range(0, 4);
// x: [[0, 1], [2, 3]]

const y = x.slice(0, 2);
// y: [0, 1]

const z = v.ones(2);
// z: [1, 1]

y.add(z);
// y: [1, 2]

// x: [1, 2, 2, 3]