Do not build factories if units can't reach enemy from their positions

[slogic]

We need some algorithm to avoid building vehicle plants in holes so they can't reach enemy and even allied units. This degrades AI too much on "Small Supreme Battlefield Dry" map. Also AI can build vehicle plant on the hill on "Desert Triad" map which is very stupid too.

[Error323]

It is not really a degradation imo, more like a behaviour/request issue. Degradation is when something was better in the past and got degraded after some change. As far as I know, this has always been a problem.

[slogic]

Ok, changed issue text to present time.

[MisterBenn]

Just as a heads up: some labs like the Core T2 bot lab allow smaller units like the pyro to exit to the North or South when built facing East, but larger units like the Sumo get stuck exiting east when built flush against something and stop the lab building. You might need to test for multiple cases or perhaps just the worst.

[slogic]

Test is simple: get route to target. That is all. The hard one is what path type to select which should represent most of units of upcoming factory. The other hard one is which target to select.