Update 2048 tutorial to KorGE 3.0

[soywiz]

No description provided.

[dfyz8-g]

Hello, Korge team
Could you write how long it will take?
I'm starting to explore korge, but as I've understood, the current 2048 game tutorial is not compatible with new korge version.
I can swap non-working code to working code independently, but I'm not sure that it will be correct. I mean that code will be work, but possible I will violate some rules/principles of engine. I want to use your game engine correct.
Thanks

[idle-code]

It would be nice to have it in the repo too - so it could be updated with the rest of the code

[krisbitney]

I've just completed the tutorial. There are two breaking changes I've encountered so far that I would say aren't minor.

1. The tutorial code doesn't result in centered score values as pictured, which is kind of annoying. But it seems like a bug in KorGE, not in the tutorial. If it's not a bug, I think a method named centerXOn is very misleading!

2. The whole UI Skin model has been reworked since the tutorial was written, and it took a lot of digging to learn how to get the desired behavior. Compare the tutorial code in the "Game over overlay" section to my own:

fun Container.showGameOver(onRestart: () -> Unit) = container {
    position(leftIndent, topIndent)

    fun restart() {
        this@container.removeFromParent()
        onRestart()
    }

    roundRect(fieldSize, fieldSize, 5.0, fill = Colors["#FFFFFF33"])
    text("Game Over", 60.0, Colors.BLACK, font) {
        centerBetween(0.0, 0.0, fieldSize, fieldSize)
        y -= 60
    }
    uiText("Try again", 120.0, 35.0) {
        centerBetween(0.0, 0.0, fieldSize, fieldSize)
        y += 20

        uiSkin = UISkin {
            textColor = RGBA(0, 0, 0)
            textSize = 40.0
            font = font
        }
        onOver {
            textColor = RGBA(90, 90, 90)
        }
        onOut {
            textColor = RGBA(0, 0, 0)
        }
        onDown {
            textColor = RGBA(120, 120, 120)
        }

        onClick { restart() }
    }

    keys.down {
        when (it.key) {
            Key.ENTER, Key.SPACE -> restart()
            else -> Unit
        }
    }
}