GameOver and Shop improvement

Two new improvements added:

1. GameOver screen
   A very missing feature was the GameOver and restart screen. Now it's added. It just shows the reached population and offers a Game replay possibility. A High score is still missing and will be added after population game balancing.
2. Shop icon improvement
   Just a little lock icon above the locked house to improve the visualization. This was a low hanging fruit that I just fixed with this update.

Thanks for following! :-)