Added some randomising to ELO sorting

Players within 20 ELO of each other may end up in different places each
time players are sorted, even if the same players are being sorted each
time. Also changed the behaviour so that the top most ELO player is not
always placed on aliens.
Hook improvements

Less garbage data per call, more future proof and sensible chat hook.
Merge pull request #110 from Person8880/develop

ELO sorting changes and hook improvements