Add #SELECTABLE:YES, NO and ROULETTE.

Add an option for this.  It's off by default.

stepmania/src/ScreenSelectGroup.cpp

@@ -74,8 +74,11 @@ ScreenSelectGroup::ScreenSelectGroup()
 		NotesType nt = GAMESTATE->GetCurrentStyleDef()->m_NotesType;
 		for( i=aAllSongs.GetSize()-1; i>=0; i-- )		// foreach Song, back to front
 		{
-			if( !aAllSongs[i]->SongHasNotesType(nt) )
-				aAllSongs.RemoveAt( i );
+			if( aAllSongs[i]->SongHasNotesType(nt) && 
+				aAllSongs[i]->NormallyDisplayed() )
+				continue;
+
+			aAllSongs.RemoveAt( i );
 		}
 	}