Indicate overlapping workareas while placing a constructionsite

[GunChleoc]

While placing a construction site, indicate whether its workarea overlaps with another workarea, so that the player will know that a forester will plant trees on a farm's field spots, for example.

This could be done by giving the overlapping parts of the workarea overlay a different color, e.g. red.

Forum discussion: https://wl.widelands.org/forum/topic/4499

[Benedikt Straub (nordfriese)]

I see a potential problem here: Since workareas can theoretically have any radius, we will need to iterate over all buildings of the player on the map to check for overlaps. That may be slow. Do we want to define a constant X so that a building with overlapping workarea will be ignored if it is further than X away from the new site?

Should we also indicate overlaps with buildings of other players if they are visible? (Useful e.g. for militarysites)

[GunChleoc (gunchleoc)]

The tribes have the workarea information for each building. So, we could calculate a maximum workarea value when loading the tribes and use that as a radius for surrounding buildings.

[GunChleoc (gunchleoc)]

Migrated to https://github.com/widelands/widelands/issues/2133