Add menu background.

osu.Game.Resources/osu.Game.Resources.csproj

@@ -91,6 +91,10 @@
     <EmbeddedResource Include="Textures\Cursor\cursor%402x.png" />
     <EmbeddedResource Include="Textures\Cursor\cursor.png" />
   </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="Textures\Menu\background%402x.jpg" />
+    <EmbeddedResource Include="Textures\Menu\background.jpg" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.