#58 Dataset expanding to multiples of 4

[F Weisp]

A dataset with the length of 9 byte leads to 7 zeros in the end of the packet.

1. four zeros can be assigned to [#57]
2. The three other come from the padding logic:

   If the user data length is not a multiple of 4 octets,
   octets with a value of 0 (zero) should be appended
   until a multiple of 4 octets is reached (padding
   bytes).