add functions/vendor files

vendor/golang.org/x/text/width/kind_string.go

@@ -0,0 +1,16 @@
+// Code generated by "stringer -type=Kind"; DO NOT EDIT
+
+package width
+
+import "fmt"
+
+const _Kind_name = "NeutralEastAsianAmbiguousEastAsianWideEastAsianNarrowEastAsianFullwidthEastAsianHalfwidth"
+
+var _Kind_index = [...]uint8{0, 7, 25, 38, 53, 71, 89}
+
+func (i Kind) String() string {
+	if i < 0 || i >= Kind(len(_Kind_index)-1) {
+		return fmt.Sprintf("Kind(%d)", i)
+	}
+	return _Kind_name[_Kind_index[i]:_Kind_index[i+1]]
+}