Add alert on beacon overload

[kyran-z]

As title says, sometime you put down a new beacon or change setting and don't realize some machines are left stuck due to another beacon that's in range. Adding an alert to point to point you to machines stuck would be nice

[charleycrissman]

Bumping this as I think it's a really good idea. The icon is easy to miss (and pretty low-contrast against a lot of the buildings). The beacons (especially non-diet ones) have a big range that means they often affect things that aren't even on your screen. I've had at least a dozen instances where my factory was stopped by beacon interference that I missed.

An alert would be a huge improvement.