[Request] Add a Defend Fleet order

[Pesanur]

Currently we have the Defend Commander order, that is ok, but having also a Defend Fleet order can be awesome.

THis way the Defend Commander order, defend only the commander ship, while the Defend Fleet orderm can defend any ship in the fleet that is under attack, independently of if is a direct subordinate of the same main commander or is a subordinate or any other ship in the fleet.

[Raptor34]

That's already how it works. The only part where it doesn't work is that it works only in a radius of it's immediate commander.