A simple mod that adds a /fly command to allow you to fly no matter the gamemode (or not)
Usage
/fly [<players>] [<state>]
If no players are specified the command will target the user.
If no state is specified the command will toggle the flight state of the target.
This will fail if there are multiple targets.
Languages
Currently English and Dutch are supported.
If the client does not have the mod installed the language of the server will be used.
(On a dedicated server this is likely English, in a LAN world it is the current language of the host.)
