add cmd/dump - a dumper

Walk needed to be added to NeedleMap and CompactMap, to be able to add WalkKeys and WalkValues to volume. This is needed for iterating through all the stored needles in a volume - this was dump's purpose.

weed-fs/src/pkg/directory/file_id.go

@@ -3,8 +3,8 @@ package directory
 import (
 	"encoding/hex"
 	"pkg/storage"
-	"strings"
 	"pkg/util"
+	"strings"
 )
 
 type FileId struct {
@@ -16,14 +16,14 @@ type FileId struct {
 func NewFileId(VolumeId storage.VolumeId, Key uint64, Hashcode uint32) *FileId {
 	return &FileId{VolumeId: VolumeId, Key: Key, Hashcode: Hashcode}
 }
-func ParseFileId(fid string) *FileId{
+func ParseFileId(fid string) *FileId {
 	a := strings.Split(fid, ",")
 	if len(a) != 2 {
 		println("Invalid fid", fid, ", split length", len(a))
 		return nil
 	}
 	vid_string, key_hash_string := a[0], a[1]
-  volumeId, _ := storage.NewVolumeId(vid_string)
+	volumeId, _ := storage.NewVolumeId(vid_string)
 	key, hash := storage.ParseKeyHash(key_hash_string)
 	return &FileId{VolumeId: volumeId, Key: key, Hashcode: hash}
 }