Prefer to target things in a more sensible order. High value targeting slots should prioritize 'in range' targets: Battlecruiser, battleship then cruisers

low value targeting slots should prioritize frigates first then cruisers
Fix for previous commit, and adds an adjustment to GetBestTarget to shoot cruisers last.
Do not try to loot any wreck that are not already in loot range if you dont have any tractors fit, there is nothing that moves us around the field at this point...