BugFix #2657 win10 1903 黑色主题下， trayIcon 会消失的问题；

https://github.com/shadowsocks/shadowsocks-windows/issues/2657

Support Windows 10 1903 Light Theme

But Fix Support Windows 10 1903 Dark Theme

shadowsocks-csharp/View/MenuViewController.cs

@@ -66,7 +66,7 @@ namespace Shadowsocks.View
         // color definition for icon color transformation
         private readonly Color colorMaskBlue = Color.FromArgb(255, 25, 125, 191);
         private readonly Color colorMaskDarkSilver = Color.FromArgb(128, 192, 192, 192);
-        private readonly Color colorMaskLightSilver = Color.FromArgb(192, 192, 192, 192);
+        private readonly Color colorMaskLightSilver = Color.FromArgb(192, 192, 192);
         private readonly Color colorMaskEclipse = Color.FromArgb(192, 64, 64, 64);
 
         public MenuViewController(ShadowsocksController controller)