SoundBuffer: Set song volume

- Requires a new column in the database after preview: `volume` REAL
- The value is a volume multiplier, if the value is set to null or 1 there will be no change
- The volume can be set in debugger
- Imported TJA files are now read from disk every time the song is played, freeing some memory and making it easier to create charts
- Correctly parse TJA files with alphabet notes, added "A" and "B" notes, which appear as DON (Big) and KA (Big) respectively

public/src/js/view.js

@@ -1438,7 +1438,7 @@
 			ctx.fill()
 			ctx.globalAlpha = 1
 		}
-		if(!circle.animating){
+		if(!circle.animating && circle.text){
 			// Text
 			var text = circle.text
 			var textX = circlePos.x