Added the /sponsor (and opposites) + admin commands

Devlog #2 for Sponsor system
Alright, so the /sponsor command is now in, which means you can sponsor a player, which will make you co-responsesible for that players bad actions on the server. Each player gets 10 tickets for invites/sponsoring, meaning you shall choose wisely who you back up.
Alongside this command you can also /uninvite or /unsponsor a player (both commands do the same) to stop sponsoring them.
For the admin commands - there is /viewtree which allows you to see who sponsors who and whos sponsored by who. All usernames here are clickable, which makes the experience a bit better.
And that’s about it I think.