Minor modifications to routes and spaces, from feedback:
Added nobuild to tanks above mid doorways.
Removed underground bypass from 3 to 5.
Removed underground route from below 5 to behind 5.
Added cover to 4 to make it more enjoyable for vulnerable players.
a2b was a quick edit that addressed the largest and easiest-to-fix gripes of play testers of a2a. They should change the action around 5 a lot, since attackers can no longer bypass 4 on their way to 5 from their 2nd forward spawn, and they can no longer flank underneath defenders at 5 and come out behind them.