Added spectator game mode check. Added new onJoin event listener. Add…

…ed new config.yml variable `defaultJoinTrailStringName: "ColoredRedDust"`. Added new default trail on join system. Added new permission node `trailgui.*`. Added new permission node `trailgui.bypass.*`. Added new permission node `trailgui.bypass.jointrail. Changed plugin version to `6.16.4-CUSTOM`.