Shouldn't https://github.com/Minestom/Arena/blob/aee77686437fdaf24310d60a996de8a08e0b7370/src/main/java/net/minestom/arena/feature/BowFeature.java#L30-L36 use the instance world age rather than current time millis?

The demo server is configured to restart at 00:00 every day in order to fetch updates, however this currently causes all players to be disconnected immediately, this PR solves that by waiting for all games to finish and prevents new ones from starting if a shutdown is initiated.

Adds 4 NPCs to the lobby, three for links to website, Discord and this repo and another one for starting a game. I also split the lobby class into multiple since it was getting quite big.

• [x] Fix evoker looking at players in a different instance (resolves #50)
• [x] Update AI methods to not use their deprecated counterparts
• [x] If you leave during round start countdown, you still receive the countdown/items/armour
• [x] If you disband/are not in a group then create a new group you don't have the scoreboard/sidebar
• [x] Confusing messages when setting another player to group leader and you aren't the leader
• [x] Make the process for joining a group when you have an existing group less spammy
• [x] If the size of a group is > 16, the scoreboard lines will go over the max and cause errors. Replace this with a ... 5 more

[Ms-Tick-0] [01:52:09] (Main.lambda$main$7) - ERROR - Global exception handler: java.lang.IllegalArgumentException: Entity can look at another entity that is within it's own instance
        at net.minestom.server.utils.validate.Check.argCondition(Check.java:36)
        at net.minestom.server.entity.Entity.lookAt(Entity.java:355)
        at net.minestom.arena.game.mob.EvokerMob.lambda$new$1(EvokerMob.java:32)
        at net.minestom.arena.game.mob.EvokerMob$ActionGoal.tick(EvokerMob.java:97)
        at net.minestom.server.entity.ai.EntityAIGroup.tick(EntityAIGroup.java:94)
        at net.minestom.server.entity.ai.EntityAI.lambda$aiTick$0(EntityAI.java:48)
        at java.base/java.util.concurrent.CopyOnWriteArrayList.forEach(CopyOnWriteArrayList.java:807)
        at java.base/java.util.concurrent.CopyOnWriteArraySet.forEach(CopyOnWriteArraySet.java:425)
        at net.minestom.server.entity.ai.EntityAI.aiTick(EntityAI.java:48)
        at net.minestom.server.entity.EntityCreature.update(EntityCreature.java:48)
        at net.minestom.server.entity.Entity.tick(Entity.java:540)
        at net.minestom.server.thread.TickThread.tick(TickThread.java:66)
        at net.minestom.server.thread.TickThread.run(TickThread.java:41)

on another note, that error message is pretty confusing lol, maybe "Entity cannot look at another entity that isn't within it's own instance"

• Add attack invulnerability (No longer get insta killed by a group of zombies nor can you insta kill zombies at 20cps)
• Better holograms (No longer blocks your attacks)
• Revive on stage complete (Share coins with fellow group members)
• Make skeletons attack less often

Before you could get to any stage you wanted basically, now it gets much harder at higher stages. The first few stages are still very doable by any person. I also fixed some bugs (/lobby letting you fall out of world, misleading attack indicator, MOTD for open to LAN being yellow instead of gold)

• Adds shop to mob arena
• Before next stage starts all group members must continue
• You can buy weapon and armor upgrades and health restoration
• The shop is a NPC in the center of the arena
• Made damage modifiable (Used by armor and weapon)
• Added some utilities which might come in handy for others