Minor english fix.
Misc borders-related fixes.

 - Fixed incorrect "inside" check for circular border at Y != 0.
 - Now using the current world (not the first one) for the ckecks.
 - "+3" instead of "+4" for the WB border size in circular borders.
   Avoids a teleportation on the top of the wall, because the default knockback distance is 3 blocks.
UHTimer's toString method rewritten.

Because.
Fixed "Warning timer up" message sent when the warning is cancelled/restarted.