BA: improve defender behaviour, lvl2 raid/battle priorities, bombard build
- reduce enemy units within range requirement for building bombarders
- reduce combat unit requirements for building bombarders
- switch priorities for lightning tank / bulldog production: build lightning tanks only when sufficient bulldogs exist, not the other way around (lightning tanks are not very effecient)
- allow defenders to go after attackers that are a bit of a distance from threatened buildings
- use guard command to move defenders near defendee before they're 500 away
- don't rush to defend scouts
- don't run away when hit unless below a certain health threshold