Improve GuardScanRadius

Introduce new SCOUT definition to remove the absolute biggest problem. Set to 10 rather than the old default of 26 after enthusiastic Aeolus feedback for the idea of stopping Scouts engaging when you really want them to just run on past.
Exclude Air units from the process. Transports have weapons and were affected. People use Assist with them a lot, not great.
Hard-set Harbinger, resulting in proper behaviour observed using Attack-Move VS enemy T1 PD with no fog of war.

Fixes #176 
Fixes #170