Restrict course editor to playable songs.

This does not yet deal with songs with charts
in multiple game types.

...at least, as far as I know.

src/ScreenOptionsEditCourse.cpp

@@ -145,7 +145,7 @@ void ScreenOptionsEditCourse::Init()
 	sc.m_Tutorial = SongCriteria::Tutorial_No;
 	sc.m_Locked = SongCriteria::Locked_Unlocked;
 
-	SongUtil::FilterSongs( sc, SONGMAN->GetAllSongs(), m_vpSongs );
+	SongUtil::FilterSongs( sc, SONGMAN->GetAllSongs(), m_vpSongs, true );
 
 	SongUtil::SortSongPointerArrayByTitle( m_vpSongs );
 }