Make particles range and length configurable

[fjeddy]

The particles show up a little late (Getting to close), and they vanish to quickly. Would like to see a configurable option for when the border is displayed and for how long.

In my case, I would prefer if the particles where permanent when the player is within X blocks from the border, but right now the border will quickly vaporize into thin air if you don't constantly move close to the border.

[tastybento]

Yes, there is no config right now. I can look into this.

[arphox]

I would split this issue to two parts:

1. ability configure border view distance: It is tracked by: Allow us to configure where the border pops up #45
2. the border will disappear if you don't keep moving: I propose updating this issue to track this part.

[arphox]

@tastybento could you take a look to the split proposal and advise on the implementation?

I'm thinking on running a task in the background which would run every 20-30 ticks to show particles for the player (and then removing the task when the player disconnects).
Though I would keep the logic the "on player move event" particle display, because if someone is approaching towards the barrier quickly, they may wouldn't see the border until they bump into them which is inconvenient.

As a result, there would be a running task for all players on the server, is that a problem?

Should it be done with only one task that does the job for all online players instead? I think the outcome would be the same (1 task checking N players vs N tasks checking 1 player each), but only using one task; and another advantage on this is not having to deal with the per-player task cancellation on disconnect.

Is it fine to show particles async?