x/text/unicode/runenames: allow search of rune by name

[tebeka]

What version of Go are you using (go version)?

$ go version
go version go1.12.6 linux/amd64

Does this issue reproduce with the latest release?

Yes?

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/miki/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/miki/go"
GOPROXY="https://proxy.golang.org"
GORACE=""
GOROOT="/opt/go"
GOTMPDIR=""
GOTOOLDIR="/opt/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build030318607=/tmp/go-build -gno-record-gcc-switches"

What did you do?

x/text/unicode/runenames provides a way to lookup rune name, I'd like to do the opposite and look for a rune by it's name.

What did you expect to see?

A Rune(name string) (rune, error) function

What did you see instead?

Nothing :)

[bcmills]

CC @mpvl

[mvdan]

Presumably this would only return a positive result for precise matches?