add themeMix

packages/artplayer/src/player/titleMix.js

@@ -0,0 +1,12 @@
+import { def } from '../utils';
+
+export default function titleMix(art) {
+    def(art, 'title', {
+        get() {
+            return art.option.title;
+        },
+        set(title) {
+            art.option.title = title;
+        },
+    });
+}