The 6 bytes obtained from `random_bytes()` is a 48-bit integer, which
cannot be converted to decimal on a 32-bit system, without being
implicitly cast to a float by PHP. This was causing problems with
setting the multicast bit, and it led to non-random node values.
This new approach splits the 6 bytes up into two 3-byte values, each a
24-bit integer, and applies the multicast bit to the most significant
bits before re-combining the bytes as a string.
Borrows the idea from cf1c981414 to
properly set the multicast bit to the "least significant bit of the
first octet of the node ID."
When merged, this will close#171 and #170
Ben Ramsey
Massimiliano Arione
Marco Perone
Anton Vasetskiy