Players should not take fall damage when switching between game worlds

[BONNe]

Description
If a player falls in SkyBlock, and while falling writes /ai, then he takes fall damage in AcidIsland.

Steps to reproduce the behavior:

1. Go to Skyblock.
2. Jump in the void.
3. While falling, write /ai

Expected behavior
The user should not take fall damage when he joins other worlds.

Movie
https://drive.google.com/file/d/18FU1u0omhttTGCowz9Yzbtzd4RLHZsya/view?usp=sharing

Server Information:

• YAML
• MacOS and Windows
• Java Version: Java 8
• :D Bentobox version: 1.0-SNAPSHOT
  Loaded Game Worlds:
• AcidIsland_world (AcidIsland) AcidIsland 0.5.0
• BSkyBlock_world (BSkyBlock) BSkyBlock 0.6.0

Additional context
I found it while testing #419 pull request.

[Poslovitch]

Do the player takes fall damage when he falls into the void and types /is ?

[BONNe]

Do the player takes fall damage when he falls into the void and types /is ?

Yes

[Poslovitch]

So is that more like a feature request: remove fall damage when teleporting to an island ?

[BONNe]

No, fall damage should not be applied to a user, if he goes from Skyblock to AcidLand and via-versa.
But if a user is falling in Skyblock, and teleports still inside Skyblock /is go ... then damage should be applied.

[Poslovitch]

Hmmm. I see.
However, that may appear to be "weird" to some users. What do you think @tastybento?

[tastybento]

I think this makes sense. The add-ons may want to do this themselves though by using a worldchangevent listener and removing velocity and fall ticks because it could be entirely valid that momentum should continue when you teleport in other circumstances.

I'd say this is a request on AcidIsland and BSkyBlock respectively.

[BONNe]

You have suggested to implement GameMode addon. #415

If its approved and implemented, I think it would be better there, as these changes should be equal in all addons, that works with new worlds.