move song cache into a subdir

stepmania/src/Song.cpp

@@ -277,7 +277,7 @@ float Song::GetElapsedTimeFromBeat( float fBeat ) const
 
 CString Song::GetCacheFilePath() const
 {
-	return ssprintf( "Cache/%u", GetHashForString(m_sSongDir) );
+	return ssprintf( "Cache/Songs/%u", GetHashForString(m_sSongDir) );
 }
 
 /* Get a path to the SM containing data for this song.  It might

stepmania/src/SongCacheIndex.cpp

@@ -12,7 +12,7 @@ SongCacheIndex *SONGINDEX;
 
 SongCacheIndex::SongCacheIndex()
 {
-	mkdir("Cache", 0755);
+	CreateDirectories( "Cache/Songs" );
 	CacheIndex.SetPath( "Cache/index.cache" );
 	ReadCacheIndex();
 }
@@ -50,6 +50,7 @@ void SongCacheIndex::ReadCacheIndex()
 	LOG->Trace( "Cache format is out of date.  Deleting all cache files." );
 	EmptyDir( "Cache/" );
 	EmptyDir( "Cache/Banners/" );
+	EmptyDir( "Cache/Songs/" );
 
 	CacheIndex.Reset();
 }