Fixes + %kill-weapon% support for meele messages

Fixes a problem with null pointer occurring sometimes. Though harmless, might as well assert that its not null.

1.17 Update

• Made to work against 1.17 and added in goat as goats can possibly kill you with them horns >:(
• Replaced unknown messages with not implemented messages (in future versions, this can count as a tempfix)
• Option to disable metrics (in config.yml) as some users will most likely not want this on. Turned on by default until you set the config option to false.

(Small Update)

• Update notification on join should be correct now