BA: add ground-only defensive front
BA: fix gunship and bomber bug, dedumben front
BA: place siege units behind the front line

- put siege units and AA at the front, behind the line
- do not defend cons within turtle radii
BA: fix a few bugs, add damagehandler
- try to boot units from factory even if there's only one exit and the first attempt failed
- fix bug in getting bombard positions
- add damagehandler to analyze where and how much units are damaged to tell if we're being shot with heavy plasma or nukes (not used yet)
Merge pull request #47 from zoggop/master

BA: form (currently ground-unit-only) defensive front