Inlcude strategic icons with list of planetary defences

[Axle]

At the moment when I click on a planet I can see what planetary defences / reinforcements the enemy have placed there. This is nice, except that sadly my brain is tuned for identifying units by strategic icon, not by the (much prettier) build icon.

It would be nice if the strategic icon for any planetary defence / reinforcement is placed along side its icon in the planet summary.

[Ze_PilOt]

All the interface is in place so it works.

A nicer one will come once everything else is sorted out.