Changes

Choose fallback based on confidence score
The fallback server chosen when a server goes down is now chosen based
on SubServers' confidence that the server can recieve the player in
question.
If there is a tie, the first server to achieve a high score is chosen.
Servers meeting these requirements will get the highest score currently
possible:
-> Fallback servers should not be white-listed (`Restricted: false`)
-> Fallback servers should be visible (`Hidden: false`)
-> Fallback subservers should be running
-> SubServers trusts that fallback servers connected to SubData are
online
 (commit: 52c6da2)