Option to disable custom messages

[Galarzaa90]

Some users may prefer to view level up and death messages in a simple format.

Add a new settings sucommand, so every server can opt out of custom messages. If they opt out, all their messages will be the same, for example:

• 🌟 Player advanced to level 45.
• ☠ Player died at level 76 by a demon.
• 💀 Player was killed by SomePk.