Support tmp(ts) templates with empty tiles.

OpenRA.Mods.TS/SpriteLoaders/TmpTSLoader.cs

@@ -29,6 +29,8 @@ namespace OpenRA.Mods.TS.SpriteLoaders
 			public bool DisableExportPadding { get { return false; } }
 
 			public TmpTSFrame(Stream s, Size size)
+			{
+				if (s.Position != 0)
 				{
 					Size = size;
 
@@ -51,6 +53,9 @@ namespace OpenRA.Mods.TS.SpriteLoaders
 					// Ignore Z-data for now
 					// Ignore extra data for now
 				}
+				else
+					Data = new byte[0];
+			}
 		}
 
 		bool IsTmpTS(Stream s)
@@ -60,8 +65,10 @@ namespace OpenRA.Mods.TS.SpriteLoaders
 			var sx = s.ReadUInt32();
 			var sy = s.ReadUInt32();
 
-			// Find the first frame
+			// Find the first non-empty frame
 			var offset = s.ReadUInt32();
+			while (offset == 0)
+				offset = s.ReadUInt32();
 
 			if (offset > s.Length - 52)
 			{