ctucx.git: webmusic-nginx

oopsie: add function that i forgot to commit

diff --git a/webmusic.js b/webmusic.js
@@ -142,6 +142,14 @@ function initState() {
     total = queue.length;
 }
 
+function previousTrack() {
+    if (index-- === 0)
+        index = total-1;
+    if (continuelist) {
+        playSong(queue[index])
+    }
+}
+
 function nextTrack() {
     if (++index === total)
         index = 0;