Popup message notifications. (#125)

* Popup message system v1

* Networking for the popup notifications.

Ship it.

Content.Client/Interfaces/IClientNotifyManager.cs

@@ -0,0 +1,14 @@
+using Content.Shared.Interfaces;
+using SS14.Client;
+using SS14.Shared.Map;
+
+namespace Content.Client.Interfaces
+{
+    public interface IClientNotifyManager : ISharedNotifyManager
+    {
+        void Initialize();
+        void PopupMessage(ScreenCoordinates coordinates, string message);
+        void PopupMessage(string message);
+        void FrameUpdate(RenderFrameEventArgs eventArgs);
+    }
+}