make selection of aeon building in construction more visible

[shalkya]

^ sometime we can't see the blue UI around the building (at all). it's hard to know which building are selected. The selection is hidden by the building mechanism (grey goo) of aeon. Or you need to be unzoomed to be able to notice which one are selected. We achieved to make other building than factory selectable, and this issue is quite annoying.

[Garanas]

Still an issue - we'd need to adjust the goo and the selection size of structures accordingly.