Initial QSfera import

Server/vendor/github.com/clipperhouse/uax29/v2/graphemes/README.md

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+An implementation of grapheme cluster boundaries from [Unicode text segmentation](https://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries) (UAX 29), for Unicode 17.
+
+[![Documentation](https://pkg.go.dev/badge/github.com/clipperhouse/uax29/v2/graphemes.svg)](https://pkg.go.dev/github.com/clipperhouse/uax29/v2/graphemes)
+![Tests](https://github.com/clipperhouse/uax29/actions/workflows/gotest.yml/badge.svg)
+![Fuzz](https://github.com/clipperhouse/uax29/actions/workflows/gofuzz.yml/badge.svg)
+
+## Quick start
+
+```
+go get "github.com/clipperhouse/uax29/v2/graphemes"
+```
+
+```go
+import "github.com/clipperhouse/uax29/v2/graphemes"
+
+text := "Hello, 世界. Nice dog! 👍🐶"
+
+tokens := graphemes.FromString(text)
+
+for tokens.Next() {                     // Next() returns true until end of data
+	fmt.Println(tokens.Value())         // Do something with the current grapheme
+}
+```
+
+_A grapheme is a “single visible character”, which might be a simple as a single letter, or a complex emoji that consists of several Unicode code points._
+
+## Conformance
+
+We use the Unicode [test suite](https://unicode.org/reports/tr41/tr41-36.html#Tests29).
+
+![Tests](https://github.com/clipperhouse/uax29/actions/workflows/gotest.yml/badge.svg)
+![Fuzz](https://github.com/clipperhouse/uax29/actions/workflows/gofuzz.yml/badge.svg)
+
+## APIs
+
+### If you have a `string`
+
+```go
+text := "Hello, 世界. Nice dog! 👍🐶"
+
+tokens := graphemes.FromString(text)
+
+for tokens.Next() {                     // Next() returns true until end of data
+	fmt.Println(tokens.Value())         // Do something with the current grapheme
+}
+```
+
+### If you have an `io.Reader`
+
+`FromReader` embeds a [`bufio.Scanner`](https://pkg.go.dev/bufio#Scanner), so just use those methods.
+
+```go
+r := getYourReader()                        // from a file or network maybe
+tokens := graphemes.FromReader(r)
+
+for tokens.Scan() {                         // Scan() returns true until error or EOF
+	fmt.Println(tokens.Text())              // Do something with the current grapheme
+}
+
+if tokens.Err() != nil {                    // Check the error
+	log.Fatal(tokens.Err())
+}
+```
+
+### If you have a `[]byte`
+
+```go
+b := []byte("Hello, 世界. Nice dog! 👍🐶")
+
+tokens := graphemes.FromBytes(b)
+
+for tokens.Next() {                     // Next() returns true until end of data
+	fmt.Println(tokens.Value())         // Do something with the current grapheme
+}
+```
+
+### Benchmarks
+
+```
+goos: darwin
+goarch: arm64
+pkg: github.com/clipperhouse/uax29/graphemes/comparative
+cpu: Apple M2
+
+BenchmarkGraphemesMixed/clipperhouse/uax29-8  	    142635 ns/op	 245.12 MB/s    0 B/op	   0 allocs/op
+BenchmarkGraphemesMixed/rivo/uniseg-8         	   2018284 ns/op	  17.32 MB/s    0 B/op	   0 allocs/op
+
+BenchmarkGraphemesASCII/clipperhouse/uax29-8  	      8846 ns/op	 508.73 MB/s    0 B/op	   0 allocs/op
+BenchmarkGraphemesASCII/rivo/uniseg-8         	    366760 ns/op	  12.27 MB/s    0 B/op	   0 allocs/op
+```
+
+### Invalid inputs
+
+Invalid UTF-8 input is considered undefined behavior. We test to ensure that bad inputs will not cause pathological outcomes, such as a panic or infinite loop. Callers should expect “garbage-in, garbage-out”.
+
+Your pipeline should probably include a call to [`utf8.Valid()`](https://pkg.go.dev/unicode/utf8#Valid).