Chnage version to 2.21.2

Damnit!

Change version to 2.21.1

Improve Alt Manager

It now supports unchecked alts and will no longer log you in multiple
times when adding or editing an alt. That means you will no longer get
IP-banned from Mojangs login servers, unless of course you manually log
in multiple times.

Change version to 2.20.1

Add AutoSplashPotMod tutorial

Prepare Minecraft 1.9 notice

Merge branch 'pr/2387'

Add .say reminder

Saw a lot of people still having issues with bypassing the commands.
This should help them.

🐛 Fix copyright messages

For some reason, not all of them got replaced last time.

Add AntiKnockback Strength slider