[bug added to bug list] Air Group transfer display issue

[Harain1]

This is just a display issue, where it shows incorrect numbers when transferring single air groups

To reproduce:
- start a new game as Axis
- Select any AOG on map, for example KG55
- click on the AOG's airbase (Zamosc)
- select a single air group (for example II./KG 55)
- using Shift key, mouse over an empty nearby airfield
- notice how the transfer box says 160/100 (for a small airfield)

It should say 40/100, since we're only transferring 1 air group and not the whole AOG, but it shows the full AOG size

Once you execute the transfer, it uses the correct space since it only (correctly) transferred 1 air group