Main Menu and Tutorial added

To make it easier to navigate, a main menu and tutorial should help the first-time users get introduced to the game and stuff.

Main Menu

And a tutorial that looks like this:

Tutorial (first page, there are multiple pages)

The deadline is coming up quickly. The quality of the code goes down, as the focus is on pushing in all the features, not making the "cleanest" implementation. The game does work quite well in recent playtesting session, and the small things added in the last days add a lot to the experience (in our opinion).