UI - Fixed potential issue with fullscreen apps

Removed the MainWindowHandle constant as it was causing issues in combination with the tray icon

src/Artemis.Core/Services/CoreService.cs

@@ -125,11 +125,6 @@ namespace Artemis.Core.Services
             });
         }
 
-        public void SetMainWindowHandle(IntPtr handle)
-        {
-            Constants.MainWindowHandle = handle;
-        }
-
         protected virtual void OnFrameRendering(FrameRenderingEventArgs e)
         {
             FrameRendering?.Invoke(this, e);

src/Artemis.Core/Services/Interfaces/ICoreService.cs

@@ -46,11 +46,5 @@ namespace Artemis.Core.Services.Interfaces
         ///     Occurs whenever a frame is finished rendering and processed by RGB.NET
         /// </summary>
         event EventHandler<FrameRenderedEventArgs> FrameRendered;
-
-        /// <summary>
-        /// To be called by the UI to setup the main window handle
-        /// </summary>
-        /// <param name="handle"></param>
-        void SetMainWindowHandle(IntPtr handle);
     }
 }