Fix busted unicode (emoji? chinese characters?) support

[bitspittle]

Well, nuts. String.length miscounts unicode characters and we might be using it everywhere.

Something like this should render incorrectly

bordered {
   textLine("Hello")
   textLine("Oh my stars ⭐⭐⭐ this just screws it up")
   textLine("Goodbye") 
}

Add stars to test cases, and probably use text.codePoints.count() instead of text.length. Audit all the code...

[bitspittle]

Not a blocker for 1.0.

It's not great, sure, but emojis (many of them anyway) work, and it's in some ways more cosmetic than fundamental. Plus, we can always fix it in the future and the change should be backwards compatible with older codebases.

[mstrobel]

FYI, this is an especially tricky/vexing issue—the Unicode standard gets updated all the time, and making sure you measure emojis correctly (especially combining sequences like person + hat + skin color) usually means interoperating with a native library. And then there’s East Asian character sets, but at least those don’t change multiple times a year.

[bitspittle]

Even worse than I thought 😂 I have given up on this one at the moment. I looked briefly into the places I was using str.length and I recall some case being tricky to handle. I probably should have left a note on this bug what that was...

But yeah I guess first pass would be finding the right third party library to include which did the counting for me.

[bitspittle]

Report from a user. This looks like it's actively causing a program when trying to repaint Chinese characters:

Not working:
https://user-images.githubusercontent.com/43705986/228932658-9ebe0622-0bf2-4157-b193-c6008eaa01e9.mp4

Working:
https://user-images.githubusercontent.com/43705986/228932683-3fb2a15a-4e70-4e12-91a6-8a485ad23ae8.mp4

Code to reproduce:

var success by liveVarOf<Boolean?>(null)
var errorMsg by liveVarOf<String?>(null)

val blinkTotalLen = 1.seconds
val blinkLen = 250.milliseconds
var blinkOn by liveVarOf(false)

section {
    textLine("Please input:")
    items.forEach { codeData -> textLine("  $codeData") }
    text("> "); input()
    success?.let {
        p {
            if (!it)  {
                red { text("×") }; text(" ")
                scopedState {
                    red(isBright = true) {
                        if (blinkOn) invert()
                        textLine("LKJLKJLJLKJLKLHJKHJSLKDJLKSJDLKSJDLKSNM<ADLKSJKDLJSLKDJKLAJSLKAJKLJLKSKLSHFKLSJDKLAJSDLKAJDKLSJDLKSFLJKSHKLFHKLSJDLKAJSLKAJLKJKLSFKLHSKLFJKLS")
//                            textLine("错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误错误")
                        textLine("caused by: ${errorMsg?: ""}")
                    }
                }
            }
        }
    }
}.runUntilSignal {
    onInputEntered {
        if(input.any { !it.isDigit() }) {
            errorMsg = "error "
            success = false
            rejectInput()
            var blinkCount = blinkTotalLen.inWholeMilliseconds / blinkLen.inWholeMilliseconds
            addTimer(blinkLen, repeat = true) {
                blinkOn = !blinkOn
                blinkCount--
                if (blinkCount == 0L) {
                    repeat = false
                }
            }
        }
    }
}