Add a number of small helper functions to Lua API

OpenRA.Mods.RA/Scripting/Global/MapGlobal.cs

@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using System.Linq;
 using Eluant;
 using OpenRA.Scripting;
@@ -43,6 +44,34 @@ namespace OpenRA.Mods.RA.Scripting
 			return actors.ToLuaTable(context);
 		}
 
+		[Desc("Returns a table of all actors within the requested rectangle, filtered using the specified function.")]
+		public LuaTable ActorsInBox(WPos topLeft, WPos bottomRight, LuaFunction filter = null)
+		{
+			var actors = context.World.ActorMap.ActorsInBox(topLeft, bottomRight)
+				.Select(a => a.ToLuaValue(context));
+
+			if (filter != null)
+				actors = actors.Where(a =>
+				{
+					using (var f = filter.Call(a))
+						return f.First().ToBoolean();
+				});
+
+			return actors.ToLuaTable(context);
+		}
+
+		[Desc("Returns the location of the top-left corner of the map.")]
+		public WPos TopLeft
+		{
+			get { return new WPos(context.World.Map.Bounds.Left * 1024, context.World.Map.Bounds.Top * 1024, 0); }
+		}
+
+		[Desc("Returns the location of the bottom-right corner of the map.")]
+		public WPos BottomRight
+		{
+			get { return new WPos(context.World.Map.Bounds.Right * 1024, context.World.Map.Bounds.Bottom * 1024, 0); }
+		}
+
 		[Desc("Returns a random cell inside the visible region of the map.")]
 		public CPos RandomCell()
 		{