Add minimum auto claim size

[Jikoo]

Default minimum is 0 to match existing behavior.

Closes #370

[RoboMWM]

Can you provide a short blurb to add to the wiki?

[Jikoo]

Claims.AutomaticNewPlayerClaimsRadiusMinimum: 0

When a player would be eligible for an automatic claim via chest placement, the automatic claim's radius will shrink until it does not conflict with existing claims. This configuration variable allows server owners to define a minimum radius that must be clear of other claims.

[Jikoo]

Realized while I was poking at the wiki to match the blurb style that someone will for sure set this new node higher than the auto claim radius and wonder why it doesn't work. Then, when I looked at that I realized I forgot to include the node in the out config because I'd manually put it in for testing. Will submit fixes later today.