Set a default border that is automatically created around the spawn point of each world.

This is especially useful for mods that generate can generate infinite new worlds, such as Galacticraft (space stations) or Mystcraft.

This would be a nice feature add.

Issue #47 looks like it would be a good feature request if you wanted a bonus round.

I'd also really like to see this. Preferably with customizable options for Overworld/Nether/End/Others instead of just one default for all. Would like to have smaller world borders on my spacestations than in the overworld.