- our db_test tests now use psql version 15 (which is the same
version our docker-compose file uses) for consistency.
- also added another test, TestDBPlayer
- added Chunk.ForEachEntity()
- refactored SendPacketExclude() to use it
- Chunk.Entities is now Chunk.entities, which is private.
- Chunk.AddEntity() && RemoveEntity() now lock the chunk mutex