Add bodyblocking as a feature proper

I did [say that it is officially a feature](http://www.ganggarrison.com/forums/index.php?topic=34094.msg1172015#msg1172015), plus [new strategies and tactics are appearing as a result of it](http://www.ganggarrison.com/forums/index.php?topic=34103.0)

I think we should keep it in next release instead of removing it. Not to troll, but because I think it is a genuinely interesting game change, although it does cause some new balance issues.