Fix case issues like Temperat vs TEMPERAT during map import.

OpenRA.Mods.Common/UtilityCommands/ImportLegacyMapCommand.cs

@@ -60,7 +60,8 @@ namespace OpenRA.Mods.Common.UtilityCommands
 				var format = GetMapFormatVersion(basic);
 				ValidateMapFormat(format);
 
-				var tileset = GetTileset(mapSection);
+				// The original game isn't case sensitive, but we are.
+				var tileset = GetTileset(mapSection).ToUpperInvariant();
 				Map = new Map(modData, modData.DefaultTileSets[tileset], MapSize, MapSize)
 				{
 					Title = basic.GetValue("Name", Path.GetFileNameWithoutExtension(filename)),