Anti-basewalk balance adjustments

Making this a pull request because I would like some opinions on these changes and some testing done. They generally make defenses bad against wooden structures which will discourage basewalking and make basewalking more difficult. Because some structures like `fact` and the superweapons are heavy I have moved them over to wood and given them a health boost. pbox and hbox have been moved over to heavy from wood. I have left the pillbox weapons unchanged.