Wire up the "change pack" button

index.html

@@ -22,8 +22,10 @@
     <header id="header-pack">
         <h2 id="level-pack-name">Chip's Challenge Level Pack 1</h2>
         <nav>
-            <button class="set-nav-return" type="button" disabled>Change pack</button>
+            <button id="main-change-pack" type="button">Change pack</button>
+            <!--
             <button id="player-edit" type="button">Return to editor</button>
+            -->
         </nav>
     </header>
     <header id="header-level">