Updated physics and store UI

I have updated the physics in the game, along with the upgrade system, I am fairly happy with where these are at for the moment.

I have also updated the shop UI with some colors and graphics.

I implemented the saving and loading of some extra data, as well as the ability to reset the saved data, but I appear to have introduced a bug somewhere, as data which was previously saving is not saving any more, I will need to fix this before submitting and releasing the game.