title: How to convert vector of integers to and from bytes?
body: <p>How can I convert <code>Vec&lt;u32&gt;</code> to bytes, such that <code>[1, 2, 4]</code> should give me <code>[1, 0, 0, 0, 2, 0, 0, 0, 4, 0, 0, 0]</code>, and to take the inverse bytes and convert them back to a vector of integers?</p>
  <p>I only know how to convert <code>[u8; 4]</code> into an integer.</p>