Allow building the same building on top already queued one.

[Pokute]

This is a QoL feature for when you have a lot of queued buildings ready, but want to hurry up a separate one. For example, imagine having queued 3 mexes quite far away from each other for engineer A. Engineer A is building the first mex, but you have engineer B close to the second mex. Currently you have to cancel the second mex to build it with engineer B.

This feature would allow to place the build order on top of existing queued (ghost) building and it would preferably take the build order of that mex from engineer A and add it into engineer B's build queue. This would mean that engineer A could still come and assist engineer B in building the second mex and after that continue to the third mex.

A bit worse alternative would be to drop the build from engineer A's queue completely and only have engineer B build the mex.

This would use the "copy build queue" feature that was added recently. I looked into this myself, but it looked like it would require a binary patch so this would in no way be an easy change.

Finally, the most awesome thing would be if this worked on mex capping so that you could add engineers to capping process without canceling the storages. Of course one could assist the engineers that do the initial capping, but that might mean a lot more travel time instead of starting off the capping the nearest mex.

Of course, this should work for every kind of building as long as same building is put on top of the queued (ghost) one.