Make actors outside map borders selectable for their owner

PR #5967 only made planes not lose their selection when they strayed
outside the map border. This PR makes it possible to select them when
they already are outside the map.

Fixes #5651 for real, then.
It is related. Deniz complained that the pups disappeared when a plane enters a shroud. Another thing that disappears is the rank decoration. This change ensures that the rank is visible for your units under the shroud as well. It won't do this for enemy units as affiliation is checked in the statement before this.
If I didn't remove this, you could expect the next complaint on irc to come within hours.