[Steps] Fix a bug where e.g. ".SM" ".DWI" ".Sm" ".sM" files wouldn't properly load since the code was expecting lowercase.

Docs/Changelog_sm5.txt

@@ -8,6 +8,11 @@ ________________________________________________________________________________
 StepMania 5.0 $next | 2011xxxx
 --------------------------------------------------------------------------------
 
+2011/10/12
+----------
+* [Steps] Fix a bug where e.g. ".SM" ".DWI" ".Sm" ".sM" files
+  wouldn't properly load since the code was expecting lowercase. [AJ]
+
 2011/10/10
 ----------
 * [NotesLoaderBMS] Add the time signature segments. [theDtTvB]

src/Steps.cpp

@@ -105,6 +105,8 @@ bool Steps::GetNoteDataFromSimfile()
 	// Replace the line below with the Steps' cache file.
 	RString stepFile = this->GetFilename();
 	RString extension = GetExtension(stepFile);
+	extension.MakeLower(); // must do this because the code is expecting lowercase
+
 	if (extension.empty() || extension == "ssc") // remember cache files.
 	{
 		SSCLoader loader;