Infinity mode highscore and controls explanation

Adding an alpha version of x2-0 to itch.io was a really good lesson. People had all sorts of problems with stuff I didn't notice or care enough, as I know the way around them. Notably:

• the "Infinite Mode", which is currently quite far from ready (I planned to focus on it after finishing all levels from History Mode) received a lot of attention -- something that it was definitely not ready for; and
• the controls, which seemed so intuitive to me (not only as the developer, but also as an old time player of That Old Copter Flash Game), apparently are very confusing to other players.

That being the case, I fixed a bug on Infinite Mode where the game would fail to restart after a crash. Now, upon crashing the ship, the game will prompt a highscore screen and the player will be able to try again.

As for the controls, I added a button on the title screen which leads to a demonstration of the game mechanics, both using the touchscreen (for mobile gameplay) and the keyboard.