Is your feature request related to a problem? Please describe.
This basically goes hand in hand with #60 trying to prevent VoxelSniper from doing things when I don't specifically want it to.
Some servers have terribly long uptimes or just want to stop persisting sessions over every logout/login so the said solution below would be nice.

Describe the solution you'd like
Configuration option to remove the sniping session of a player upon logout/login

Describe alternatives you've considered
See #60