Force Appear

Title says it all.

Added config option to allow worlds to save state. Set it so it will remember state when you leave a world and revert when you return. So if you are invisible in worldA and you go to worldB, if worldB doesn't allow invisibility it sets you back to visible. Without state saving, if you go back to worldA where you were invisible you'd still be visible as the system set you that way already. If state save is on, it will remember that you were invisible when you left worldA and automatically make you invisible when you return. Also added config option to make this apply to ops. By default it doesn't apply to ops because they have all permissions so they will have the exemption permission automatically. By setting this true, it will require the explicit permission even if they are op.

Added a check so if the player has forceappear.exempt, it doesn't screw with their visibility setting