Added crude client rendering with pixi.js

Added keyboard controlling
Added fixed ball reflections on right paddle
added reflections on screen borders
Added goal (miss the paddle) detection

PongGame/Pages/Pong.cshtml

@@ -20,8 +20,11 @@
     <input id="username" type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="setusername">
     <button id="setusername" class="btn btn-outline-secondary" type="button">Set Username</button>
   </div>
+
+  <div id="canvas-container" class="mb-3"></div>
 </div>
 
 <script src="~/lib/signalr/dist/browser/signalr.min.js"></script>
 <script src="~/lib/signalr/dist/browser/signalr-protocol-msgpack.min.js"></script>
+<script src="~/lib/pixi/dist/pixi.min.js"></script>
 <script src="~/js/pong.js"></script>