Error when loading a `.npy` file containing a scalar value

[thalesfm]

Due to an off-by-one error, np.load fails to parse the file's header when shape = () and triggers an ArgumentOutOfRangeException
(Also, the function doesn't consider this possibility when calculating the size of the underlying buffer).

[Nucs]

Related to #597

[Nucs]

Fixed by #617 (the byte-identical np.save/np.load port), in 0.70.0 (#628). A shape=() scalar loads correctly now, no off-by-one:

np.save("scalar.npy", np.array(5.0));

var x = np.load_npy("scalar.npy");
Console.WriteLine(x.ndim);          // 0
Console.WriteLine(x.GetDouble(0));  // 5

Closing.