Implement progress bar for scans as well

* Remote repositories may take a while to scan, so give the user a little bit of feedback while we do so

src/cmds/restic/cmd_restore.go

@@ -136,7 +136,7 @@ func runRestore(opts RestoreOptions, gopts GlobalOptions, args []string) error {
 
 	Verbosef("restoring %s to %s\n", res.Snapshot(), opts.Target)
 
-	stat, err := res.Scan()
+	stat, err := res.Scan(newScanProgress(gopts))
 	if err != nil {
 		return err
 	}

src/restic/restorer.go

@@ -41,16 +41,24 @@ func NewRestorer(repo Repository, id ID) (*Restorer, error) {
 }
 
 // Scan traverses the directories/files to be restored to collect restic.Stat information
-func (res *Restorer) Scan() (Stat, error) {
+func (res *Restorer) Scan(p *Progress) (Stat, error) {
+	p.Start()
+	defer p.Done()
+
 	var stat Stat
 
 	err := res.walk("", *res.sn.Tree, func(node *Node, dir string) error {
+		s := Stat{}
 		if node.Type == "dir" {
-			stat.Add(Stat{Dirs: 1})
+			s.Dirs++
 		} else {
-			stat.Add(Stat{Files: 1, Bytes: node.Size})
+			s.Files++
+			s.Bytes += node.Size
 		}
 
+		p.Report(s)
+		stat.Add(s)
+
 		return nil
 	})