Feature: Intro Screen - Githubissues

Add intro screen to the game, containing:

Game Intro screen, similar to Geocentric Revolution: https://gamejolt.com/games/geocentric_revolution/770633#screenshot-1425555
Intro to the game, can use README
Controls explanation, can use README
Goal of the game - Explain that Jasna Gora is the target, cannot win the game otherwise (!!!)

MattSzymonski / HackYeah22