[Feature] Make world border visible

[sbienkow]

Since the border isn't visible, it can be annoying for some players and makes issues like #115 more common.

This could be solved by either adding a warning when a player gets within configurable distance to the border or spawning some particle effects where the border is (in a sane amount, just to mark where the border is and not lag the server / client).

This would be an optional feature, that's off by default.

Any thoughts? Ideas?

I can create PR for that, if it gets accepted and I have some more time.

[Brettflan]

It's been considered a few times, and might still happen.

#107

[Bobbbe]

I would like to have that too for our server, was that created?

[mrfloris]

Voting +1 for this. It would be nice if it could work together with the vanilla wb as a 'true' toggle to set and visualize it for that world. Or indeed to have a 'you're nearing the worldborder soon..' action msg or whatever (even if it is just once)