Added TicTacToe in Samples

Here's just one more sample — a tic tac toe game! 

It runs easily with `jruby -J-XstartOnFirstThread shoes4/bin/ruby-shoes shoes4/samples/simple-tictactoe.rb`.
So when the game is over you're creating a bunch of elements here, which requires you to pass the `app` down through things.

Do you think it's possible that we could create all those elements in the main `Shoes.app` and then just call `hide` on them? Then all we'd need to do here is potentially set the `title` text and `show` all the things we already made.

This is nice too because we wouldn't have to repeat the code for both full and over--we'd build all the stuff only once in the main app, and the over/full states just have to update the text and show things.