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/loadsong.js

@@ -112,7 +112,15 @@ class LoadSong{
 			}
 		}))
 		if(songObj.chart){
-			this.songData = songObj.chart
+			var reader = new FileReader()
+			promises.push(pageEvents.load(reader).then(event => {
+				this.songData = event.target.result.replace(/\0/g, "").split("\n")
+			}))
+			if(song.type === "tja"){
+				reader.readAsText(songObj.chart, "sjis")
+			}else{
+				reader.readAsText(songObj.chart)
+			}
 		}else{
 			promises.push(loader.ajax(this.getSongPath(song)).then(data => {
 				this.songData = data.replace(/\0/g, "").split("\n")