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/importsongs.js

@@ -183,7 +183,7 @@
 			var songObj = {
 				id: index + 1,
 				type: "tja",
-				chart: data,
+				chart: file,
 				stars: [],
 				music: "muted"
 			}
@@ -258,7 +258,7 @@
 			var songObj = {
 				id: index + 1,
 				type: "osu",
-				chart: data,
+				chart: file,
 				subtitle: osu.metadata.ArtistUnicode || osu.metadata.Artist,
 				subtitle_lang: osu.metadata.Artist || osu.metadata.ArtistUnicode,
 				preview: osu.generalInfo.PreviewTime / 1000,