Support a maximum building range (Fixes #2156).

This also implements support for a per-provider
cooldown between placing structures, allowing mods
with multiple structure queues to rate-limit
placement around a single provider.

An initial delay parameter is included to
support units that deploy into a base provider and
require an initial setup time (e.g. the Surveyor
unit from C&C TW).

The range and time restrictions are not applied to
walls as a balance choice.

OpenRA.Mods.RA/Player/PlaceBuilding.cs

@@ -80,6 +80,22 @@ namespace OpenRA.Mods.RA
 
 					queue.FinishProduction();
 
+					if (buildingInfo.RequiresBaseProvider)
+					{
+						var center = buildingInfo.CenterLocation(order.TargetLocation);
+						foreach (var bp in w.ActorsWithTrait<BaseProvider>())
+						{
+							if (bp.Actor.Owner.Stances[self.Owner] != Stance.Ally || !bp.Trait.Ready())
+								continue;
+
+							if (Combat.IsInRange(center, bp.Trait.Info.Range, bp.Actor.CenterLocation))
+							{
+								bp.Trait.BeginCooldown();
+								break;
+							}
+						}
+					}
+
 					if (GetNumBuildables(self.Owner) > prevItems)
 						w.Add(new DelayedAction(10,
 							() => Sound.PlayNotification(order.Player, "Speech", "NewOptions", order.Player.Country.Race)));