Added PREVENT_TELEPORT_WHEN_FALLING flag (WORLD_SETTING)

[Poslovitch]

Relates to #403.

I'm not sure if that's the best way to implement this though. So, I'd be glad to get as much feedback as possible (@BONNe).

By the way, handling this kind of thing is a bit tricky, so, if you wanna do some tests (which I'd also be glad, as I don't feel like testing right now), here is the build containing the changes:
bentobox-1.0-SNAPSHOT-TEST403.zip (just extract the .jar from the .zip archive).

[Poslovitch]

#403 (comment)

Now, if the flag is enabled, the players cannot use /is home (go) command when falling.

But how about going to a different world? Will going to a different world and then returning prevent a user from falling in the void?

That's right, once the flag is enabled, the player cannot us /is go when falling.

When they go to a different world, it'll just ignores that part - except if the command they're using is from, e.g. AcidIsland.

[BONNe]

To clarify my #403 comment.

If you have both addons: ai and is, then if a user is falling in Skyblock, he can write /ai and teleport to AcidIsland (by the way, user take fall damage in this situation, and it is a bug!!). And then go back to /is and be on his island, and avoids fall in the void.
Tested without enabled option. It is not allowing teleport on /ai if falling in skyblock.

I know, that it could be hard to check it, as you must teleport user to save space on world joining, so maybe, instead of checking if a player is falling you can add "timer" for teleport commands. So all teleport commands are allowed only when a caller is standing still for X seconds.

[Poslovitch]

Please create an issue for this bug, that's going to be worth investigating.

[BONNe]

So I tested this, with PREVENT_TELEPORT_WHEN_FALLING: true, and it is not working.
User still can teleport.
PREVENT_TELEPORT_WHEN_FALLING: false is working. With value False user cannot teleport.
:D

[Poslovitch]

So, I think it's all good now.

@BONNe does this PR suit your needs for #403 ?

[BONNe]

Yes, I tested it and now it works.

[Poslovitch]

Great. Just waiting for the CI to do the checks before merging.

Thanks for your reviews and your help 👍