divide by zero error for empty arrays

[hartwoolery]

thank you for the wonderful Swift library -- I have a relatively minor issue where something like MfArray([]) throws a divide by zero error. I fixed it in a fork by changing one line in shape2strides func in mfstructure.swift:

ret[index] = prevAxisNum / max(shape[index],1)

(I simply made the divisor a minimum of 1)

Let me know if I should submit a pull request or if you would like to push the change. Thank you!

[jjjkkkjjj]

Thank you for reporting!
Actually i dont care about empty MfArray.
I would be happy if you could submit a pull request about that!