build: modernize Go usage

This commit modernizes Go usage. This was done with:

go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...

Then files needed to be `go fmt`ed and a few comments needed to be
restored.

The modernizations include replacing

- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22

cmd/ncdu/ncdu.go

@@ -185,7 +185,7 @@ func (u *UI) Print(x, y int, style tcell.Style, msg string) {
 }
 
 // Printf a string
-func (u *UI) Printf(x, y int, style tcell.Style, format string, args ...interface{}) {
+func (u *UI) Printf(x, y int, style tcell.Style, format string, args ...any) {
 	s := fmt.Sprintf(format, args...)
 	u.Print(x, y, style, s)
 }
@@ -207,7 +207,7 @@ func (u *UI) Line(x, y, xmax int, style tcell.Style, spacer rune, msg string) {
 }
 
 // Linef a string
-func (u *UI) Linef(x, y, xmax int, style tcell.Style, spacer rune, format string, args ...interface{}) {
+func (u *UI) Linef(x, y, xmax int, style tcell.Style, spacer rune, format string, args ...any) {
 	s := fmt.Sprintf(format, args...)
 	u.Line(x, y, xmax, style, spacer, s)
 }
@@ -273,11 +273,7 @@ func (u *UI) Box() {
 	xmax := x + boxWidth
 	if len(u.boxMenu) != 0 {
 		count := lineOptionLength(u.boxMenu)
-		if x+boxWidth > x+count {
-			xmax = x + boxWidth
-		} else {
-			xmax = x + count
-		}
+		xmax = max(x+boxWidth, x+count)
 	}
 	ymax := y + len(u.boxText)
 

cmd/ncdu/scan/scan.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"path"
+	"slices"
 	"sync"
 	"time"
 
@@ -111,7 +112,7 @@ func newDir(parent *Dir, dirPath string, entries fs.DirEntries, err error) *Dir
 
 // Entries returns a copy of the entries in the directory
 func (d *Dir) Entries() fs.DirEntries {
-	return append(fs.DirEntries(nil), d.entries...)
+	return slices.Clone(d.entries)
 }
 
 // Remove removes the i-th entry from the
@@ -146,7 +147,7 @@ func (d *Dir) remove(i int) {
 	d.size -= size
 	d.count -= count
 	d.countUnknownSize -= countUnknownSize
-	d.entries = append(d.entries[:i], d.entries[i+1:]...)
+	d.entries = slices.Delete(d.entries, i, i+1)
 
 	dir := d
 	// populate changed size and count to parent(s)