Implement "password"-based session joining.

src/Go/Game.cr

@@ -14,11 +14,13 @@ module Go
 
     class Game
         property size : Size
+        property blackPass : String
+        property whitePass : String
         property board  : Board
         property turn : Color
         property sockets : Array(HTTP::WebSocket)
 
-        def initialize(size : Size)
+        def initialize(size : Size, @blackPass, @whitePass)
             @size = size
             @board = Board.new
             @turn = Color::Black
@@ -56,6 +58,7 @@ module Go
 
         def update(x, y, color)
             @board[{x, y}] = color
+            @turn = @turn == Color::Black ? Color::White : Color::Black
         end
 
         private def color_char(color)

src/Go/views/game.ecr

@@ -9,6 +9,9 @@
     .black-cell {
         background-color: black;
     }
+    .white-cell {
+        background-color: white;
+    }
     .board {
         max-width: 360px;
     }
@@ -22,7 +25,7 @@
         var app = Elm.Main.embed(node, {
             'black' : <%= black %>,
             'url' : "<%= "ws://" + URL + ":" + Kemal.config.port.to_s %>",
-            'id' : <%= id %>,
+            'id' : "<%= id %>",
             'size' : <%= size %>
         })
     </script>