Removed NioTSO client and server

- NioTSO client isn't needed because we're using RayLib
- Added FreeSO's API server to handle most backend operations

server/tso.common/Rendering/Framework/IO/MouseEvent.cs

@@ -0,0 +1,25 @@
+using FSO.Common.Rendering.Framework.Model;
+using Microsoft.Xna.Framework;
+
+namespace FSO.Common.Rendering.Framework.IO
+{
+    public enum UIMouseEventType
+    {
+        MouseOver,
+        MouseOut,
+        MouseDown,
+        MouseUp
+    }
+
+    public delegate void UIMouseEvent(UIMouseEventType type, UpdateState state);
+
+    public class UIMouseEventRef
+    {
+        public UIMouseEvent Callback;
+        public Rectangle Region;
+        //public UIElement Element;
+        public UIMouseEventType LastState;
+
+        public IDepthProvider Element;
+    }
+}