added sound to pong and fixed some bugs

tests/tick.erl

@@ -0,0 +1,26 @@
+-module(tick).
+-export([start/0]).
+
+start() ->
+	spawn(fun() -> loop() end).
+	
+loop() ->
+	receive
+		tick ->
+			erlang:display("tick!"),
+			timer:send_after(500, tick),
+			loop();
+		'EXIT' ->
+			exit(normal)
+	end.
+	
+% 1> c(tick).
+%  {ok,tick}
+% 2> Pid = tick:start().
+%  <0.38.0>
+% % Nothing happens :-(
+
+% When I send it myself then it responds
+% 3> Pid ! tick.
+%  tick
+% 5>