Reformatting to conform to linting standards
Set default GuardScanRadius for mobile units

Move-attack uses AI.GuardScanRadius to decide when a unit should stop and
start attacking an opponent.

If this value isn't set on a unit the following is used for weapon units:
AI.GuardScanRadius = Weapon.MaxRadius + Intel.VisionRadius

and this for engineers:

AI.GuardScanRadius =  bp.Economy.MaxBuildDistance or 10

Issue #83