Properly remove event listeners from container element (fixes #710).

For three event listeners added to the container elements weren't being
removed properly, since `removeEventListener` was mistakenly being called on
`uiContainer` instead. This was preventing garbage collection.

src/js/pannellum.js

@@ -3050,36 +3050,23 @@ function fireEvent(type) {
  */
 this.destroy = function() {
     if (renderer)
-        renderer.destroy()
+        renderer.destroy();
     if (listenersAdded) {
-        dragFix.removeEventListener('mousedown', onDocumentMouseDown, false);
-        dragFix.removeEventListener('dblclick', onDocumentDoubleClick, false);
         document.removeEventListener('mousemove', onDocumentMouseMove, false);
         document.removeEventListener('mouseup', onDocumentMouseUp, false);
-        uiContainer.removeEventListener('mousewheel', onDocumentMouseWheel, false);
-        uiContainer.removeEventListener('DOMMouseScroll', onDocumentMouseWheel, false);
         container.removeEventListener('mozfullscreenchange', onFullScreenChange, false);
         container.removeEventListener('webkitfullscreenchange', onFullScreenChange, false);
         container.removeEventListener('msfullscreenchange', onFullScreenChange, false);
         container.removeEventListener('fullscreenchange', onFullScreenChange, false);
         window.removeEventListener('resize', onDocumentResize, false);
         window.removeEventListener('orientationchange', onDocumentResize, false);
-        uiContainer.removeEventListener('keydown', onDocumentKeyPress, false);
-        uiContainer.removeEventListener('keyup', onDocumentKeyUp, false);
-        uiContainer.removeEventListener('blur', clearKeys, false);
+        container.removeEventListener('keydown', onDocumentKeyPress, false);
+        container.removeEventListener('keyup', onDocumentKeyUp, false);
+        container.removeEventListener('blur', clearKeys, false);
         document.removeEventListener('mouseleave', onDocumentMouseUp, false);
-        dragFix.removeEventListener('touchstart', onDocumentTouchStart, false);
-        dragFix.removeEventListener('touchmove', onDocumentTouchMove, false);
-        dragFix.removeEventListener('touchend', onDocumentTouchEnd, false);
-        dragFix.removeEventListener('pointerdown', onDocumentPointerDown, false);
-        dragFix.removeEventListener('pointermove', onDocumentPointerMove, false);
-        dragFix.removeEventListener('pointerup', onDocumentPointerUp, false);
-        dragFix.removeEventListener('pointerleave', onDocumentPointerUp, false);
     }
     container.innerHTML = '';
     container.classList.remove('pnlm-container');
-    uiContainer.classList.remove('pnlm-grab');
-    uiContainer.classList.remove('pnlm-grabbing');
 }
 
 }