Add support for custom locations to legacy map importer

For example, to place actors with changed footprint correctly.
Use it to ensure correct positioning of several RA and TD structures as well as TD tiberium trees.

OpenRA.Mods.RA/ImportRedAlertLegacyMapCommand.cs

@@ -126,6 +126,17 @@ namespace OpenRA.Mods.RA.UtilityCommands
 			return input.ToLowerInvariant();
 		}
 
+		public override CPos ParseActorLocation(string input, int loc)
+		{
+			var newLoc = new CPos(loc % MapSize, loc / MapSize);
+			var vectorDown = new CVec(0, 1);
+
+			if (input == "tsla" || input == "agun" || input == "gap" || input == "apwr" || input == "iron")
+				newLoc += vectorDown;
+
+			return newLoc;
+		}
+
 		public override void LoadPlayer(IniFile file, string section)
 		{
 			string color;