Tils Graves

#1 Added Decay for Gravestones

Added a decay for the graves. But don't worry! Your items will still be save forever but after the dacay time has passed other players can also open your grave and you dont need a key anymore. This has been added due to the problem that you couldnt open a grave before if you've lost your key.

#2 Performance improvement

I've narrowed down the commands run in the tils_graves:tick function to increase performance.

• the tils_graves:loot_grave function will now be called usind an advancement instead of checking every tick
• the tils_graves:create_grave function has gotten an init function to narrow down the needed commands at gamemode seperation