Fix FNA input for text

Author: prime31

src/ImGui.NET.SampleProgram.XNA/ImGuiRenderer.cs

@@ -179,7 +179,7 @@ protected virtual void SetupInput()
             //{
             //    if (c == '\t') return;
 
-            //    ImGui.AddInputCharacter(c);
+            //    ImGui.GetIO().AddInputCharacter(c);
             //};
             ///////////////////////////////////////////
 
@@ -385,4 +385,4 @@ private unsafe void RenderCommandLists(ImDrawDataPtr drawData)
 
         #endregion Internals
     }
-}
+}