Allow to tweack some setting via config file.

Initial world border size offset (in blocks) when the world is first created.

This determines the starting size of the world border. [default = 7]

SetBorderOffset = 7.0

Growth factor for the world border (in blocks) when the player gains XP levels.

This value defines how much the world border increases with each XP level gained. [default = 2]

 SetExpansionOffset = 2.0

Reduction factor for the world border size when the player dies.

For example, a value of 0.8 means the border will shrink to 80% of its current size after death. [default = 0.8]

SetReductionFactor = 0.8