Add speed control

[3Domse3]

Please add a speed control to speed up the process (like 2x, 4x 8x, 16x) to let the birds fly faster. I'm more interested in GEN 100 than in watching GEN 3 failing ;)

[tiagosomda]

@3Domse3 / @ssusnic - have you figured out how to speed up the game in Phaser?

I have been trying to do it, but the game.time.slowMotion doesn't seem to affect all the parts of the game.

This person here exactly what we want, but it is not done in Phaser which I was hoping to use.
https://tsreaper.github.io/AI-Plays-FlappyBird/