extra support for extra

source/funkin/backend/chart/ChartData.hx

@@ -51,6 +51,7 @@ typedef ChartNote = {
 	var id:Int; // strum id of the note
 	var type:Int; // type (int) of the note
 	var sLen:Float; // sustain length of the note (ms)
+	var ?extra:Map<String, Dynamic>;
 }
 
 typedef ChartEvent = {

source/funkin/game/Note.hx

@@ -117,6 +117,7 @@ class Note extends FlxSprite
 		this.isSustainNote = sustain;
 		this.sustainLength = sustainLength;
 		this.strumLine = strumLine;
+		this.extra = noteData.extra;
 
 		x += 50;
 		// MAKE SURE ITS DEFINITELY OFF SCREEN?