Merge branch 'pr/524' into 6.1.4

* pr/524:
  Refactor
  Added isHidden property for public usage

Pod/Classes/Extensions.swift

@@ -46,7 +46,6 @@ internal extension UIViewController {
         }
     }
 
-    // Indicates if the menu is anywhere in the view hierarchy, even if covered by another view controller.
     @objc var isHidden: Bool {
         return presentingViewController == nil
     }

Pod/Classes/UISideMenuNavigationController.swift

@@ -405,6 +405,11 @@ extension UISideMenuNavigationController: MenuModel {
         get { return _leftSide.value }
         set { _leftSide.value = newValue }
     }
+  
+    /// Indicates if the menu is anywhere in the view hierarchy, even if covered by another view controller.
+    open override var isHidden: Bool {
+        return super.isHidden
+    }
 
     @IBInspectable open var menuWidth: CGFloat {
         get { return settings.menuWidth }