Shop update

I have worked on some things by request from some friends so here we go!

-Added all shop items

-Added challenges

-You can now move both directions on the wall of the pool

-Changed the tutorial button to say 'Reset' because it resets your save and some players could accidentally wipe their save by pressing this button

-Some graphics have changed

-Some ending screens have more going on (for example, the lost toy ending screen as seen on the game's screenshots)

-You now get to visit the shop when you get game over

-Game works a bit better on old devices