Simultaneous unit queuing for buildings

[historic_bruno]

If multiple of the same building are selected and a unit is trained, it will only queue in the first selected building. It would be more useful if the unit was queued in each of them simultaneously. I'm not sure how to handle this when multiple different buildings are selected (probably just hide the command panel buttons in that case since it's not clear which set should be displayed).

[feneur]

That's the way most games do it that I remember yeah, if multiple different buildings are selected they just display the icons for the buildings, and (in some games at least) things they have in common. Like the possibility to see/change the rally point for all the buildings. Perhaps also deleting all, not sure if I've seen that/if it's common, but it's at least an option.

[historic_bruno]

Fixed by r11592.