Added missing MainApplication.cs file in the Xamarin Android demo.

Emgu.CV.Example/XamarinForms/Android/MainApplication.cs

@@ -0,0 +1,67 @@
+//----------------------------------------------------------------------------
+//  Copyright (C) 2004-2018 by EMGU Corporation. All rights reserved.       
+//----------------------------------------------------------------------------
+
+using System;
+
+using Android.App;
+using Android.OS;
+using Android.Runtime;
+using Plugin.CurrentActivity;
+
+namespace Emgu.CV.XamarinForms.Droid
+{
+    //You can specify additional application information in this attribute
+    [Application]
+    public class MainApplication : Application, Application.IActivityLifecycleCallbacks
+    {
+        public MainApplication(IntPtr handle, JniHandleOwnership transer)
+          : base(handle, transer)
+        {
+        }
+
+        public override void OnCreate()
+        {
+            base.OnCreate();
+            RegisterActivityLifecycleCallbacks(this);
+            //A great place to initialize Xamarin.Insights and Dependency Services!
+
+            CrossCurrentActivity.Current.Init(this);
+        }
+
+        public override void OnTerminate()
+        {
+            base.OnTerminate();
+            UnregisterActivityLifecycleCallbacks(this);
+        }
+
+        public void OnActivityCreated(Activity activity, Bundle savedInstanceState)
+        {
+        }
+
+        public void OnActivityDestroyed(Activity activity)
+        {
+        }
+
+        public void OnActivityPaused(Activity activity)
+        {
+        }
+
+        public void OnActivityResumed(Activity activity)
+        {
+        }
+
+        public void OnActivitySaveInstanceState(Activity activity, Bundle outState)
+        {
+        }
+
+        public void OnActivityStarted(Activity activity)
+        {
+
+        }
+
+        public void OnActivityStopped(Activity activity)
+        {
+        }
+    }
+}