Add singleton support for QuikApplication.

Quik/QuikApplication.cs

@@ -49,6 +49,7 @@ namespace Quik
         {
             Platform = platform;
             FontProvider = new FontProvider(this);
+            Current = this;
         }
 
         public IDisposable GetMedia(object key, MediaHint hint)
@@ -101,5 +102,12 @@ namespace Quik
                 }
             }
         }
+
+        public static QuikApplication Current { get; private set; }
+
+        public static void SetCurrentApplication(QuikApplication application)
+        {
+            Current = application;
+        }
     }
 }