Run modernize to rewrite some older go constructs to newer ones

Mostly using slice.Sort, using min/max, slices.Concat, range of int and
fmt.Appendf for byte slices instead of strings.

mox-/config.go

@@ -25,7 +25,6 @@ import (
 	"path/filepath"
 	"regexp"
 	"slices"
-	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -199,9 +198,7 @@ func (c *Config) Domains() (l []string) {
 			l = append(l, name)
 		}
 	})
-	sort.Slice(l, func(i, j int) bool {
-		return l[i] < l[j]
-	})
+	slices.Sort(l)
 	return l
 }
 

mox-/fill.go

@@ -9,7 +9,7 @@ import (
 func FillNil(rv reflect.Value) (nv reflect.Value, changed bool) {
 	switch rv.Kind() {
 	case reflect.Struct:
-		for i := 0; i < rv.NumField(); i++ {
+		for i := range rv.NumField() {
 			if !rv.Type().Field(i).IsExported() {
 				continue
 			}
@@ -18,7 +18,7 @@ func FillNil(rv reflect.Value) (nv reflect.Value, changed bool) {
 			if ch && !rv.CanSet() {
 				// Make struct settable.
 				nrv := reflect.New(rv.Type()).Elem()
-				for j := 0; j < rv.NumField(); j++ {
+				for j := range rv.NumField() {
 					nrv.Field(j).Set(rv.Field(j))
 				}
 				rv = nrv
@@ -34,7 +34,7 @@ func FillNil(rv reflect.Value) (nv reflect.Value, changed bool) {
 			return reflect.MakeSlice(rv.Type(), 0, 0), true
 		}
 		n := rv.Len()
-		for i := 0; i < n; i++ {
+		for i := range n {
 			rve := rv.Index(i)
 			nrv, ch := FillNil(rve)
 			if ch {
@@ -90,7 +90,7 @@ func FillExample(seen []reflect.Type, rv reflect.Value) reflect.Value {
 
 	switch rv.Kind() {
 	case reflect.Struct:
-		for i := 0; i < rv.NumField(); i++ {
+		for i := range rv.NumField() {
 			if !rvt.Field(i).IsExported() {
 				continue
 			}

mox-/password.go

@@ -8,7 +8,7 @@ func GeneratePassword() string {
 	chars := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*-_;:,<.>/"
 	s := ""
 	buf := make([]byte, 1)
-	for i := 0; i < 12; i++ {
+	for range 12 {
 		for {
 			cryptorand.Read(buf)
 			i := int(buf[0])

mox-/txt.go

@@ -9,10 +9,7 @@ func TXTStrings(s string) string {
 
 	r := "(\n"
 	for len(s) > 0 {
-		n := len(s)
-		if n > 100 {
-			n = 100
-		}
+		n := min(len(s), 100)
 		if r != "" {
 			r += " "
 		}