Update Mod to MC 1.16.1...
Update all build files for building 1.16.1 mod. Update Loom, MC Vers, Yarn Mappings, Loader Version, Mod Version (new format to include MC version in version name), and Fabric API version.
Utilize new Registry.DIMENSION (RegistryKey<World>) instead of old 'DimensionType's in MinecraftLocation.
Simplify file reading in 'loadPlayerData' method (PlayerDataManager class) and log certain errors when they occur.
Comment-out TradeUI for now, as changes to MC have made the existing version incompatible. Work on this feature in branch "trade-ui".
Update TeleportRequestManager to use ServerTickEvents.END_SERVER_TICK instead of deprecated ServerTickCallback event.
Small fix logging format consistency in EssentialCommands class.
Update messages to players to use ServerPlayer sendSystemMessage instead of removed ServerPlayer sendChatMessage
Use CommandRegistrationCallback instead of deprecated CommandRegistry for registering commands.
Update mixins to match Mojang's updated method signatures.
