func slashClean(name string) string {
	if name == "" || name[0] != '/' {
		name = "/" + name
	}
	return path.Clean(name)
}
slashClean is equivalent to but slightly more efficient than
path.Clean("/" + name).
package webdav
import (
	"context"
	"encoding/xml"
	"io"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"strings"
	"sync"
	"time"
)