TUN-3201: Create base cloudflared UI structure

vendor/github.com/gdamore/tcell/charset_unix.go

@@ -0,0 +1,49 @@
+// +build !windows,!nacl,!plan9
+
+// Copyright 2016 The TCell Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use file except in compliance with the License.
+// You may obtain a copy of the license at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tcell
+
+import (
+	"os"
+	"strings"
+)
+
+func getCharset() string {
+	// Determine the character set.  This can help us later.
+	// Per POSIX, we search for LC_ALL first, then LC_CTYPE, and
+	// finally LANG.  First one set wins.
+	locale := ""
+	if locale = os.Getenv("LC_ALL"); locale == "" {
+		if locale = os.Getenv("LC_CTYPE"); locale == "" {
+			locale = os.Getenv("LANG")
+		}
+	}
+	if locale == "POSIX" || locale == "C" {
+		return "US-ASCII"
+	}
+	if i := strings.IndexRune(locale, '@'); i >= 0 {
+		locale = locale[:i]
+	}
+	if i := strings.IndexRune(locale, '.'); i >= 0 {
+		locale = locale[i+1:]
+	} else {
+		// Default assumption, and on Linux we can see LC_ALL
+		// without a character set, which we assume implies UTF-8.
+		return "UTF-8"
+	}
+	// XXX: add support for aliases
+	return locale
+}