Enemy territory can only be claimed at the corners.  No more bee lines straight to bases.

Implements the border check algorithm documented at:
https://docs.google.com/spreadsheet/ccc?key=0AtzhKJgvHXCKdFZvR1hWMXZJVjg1S2RtMUQ1eC1qR0E

May need to have a config to switch between classic style and corner style.

Above doc shows a couple of other border check algorithms as well.  See the sheet tabs at the bottom.

Edit:  This is running on `factions.aethercraft.com` if you want to try it out.