Extended dbglfs.py to show file data structures

You can now pass -s/--structs to dbglfs.py to show any file data
structures:

  $ ./scripts/dbglfs.py disk -B4096 -f -s -t
  littlefs v2.0 0x{0,1}.9cf, rev 3, weight 0.256
  {0000,0001}:  -1.1 hello  reg 128, trunk 0x0.993 128
    0000.0993:           .->    0-15 shrubinlined w16 16     6b 75 72 65 65 67 73 63  kureegsc
                       .-+->   16-31 shrubinlined w16 16     6b 65 6a 79 68 78 6f 77  kejyhxow
                       | .->   32-47 shrubinlined w16 16     65 6f 66 75 76 61 6a 73  eofuvajs
                     .-+-+->   48-63 shrubinlined w16 16     6e 74 73 66 67 61 74 6a  ntsfgatj
                     |   .->   64-79 shrubinlined w16 16     70 63 76 79 6c 6e 72 66  pcvylnrf
                     | .-+->   80-95 shrubinlined w16 16     70 69 73 64 76 70 6c 6f  pisdvplo
                     | | .->  96-111 shrubinlined w16 16     74 73 65 69 76 7a 69 6c  tseivzil
                     +-+-+-> 112-127 shrubinlined w16 16     7a 79 70 61 77 72 79 79  zypawryy

This supports the same -b/-t/-i options found in dbgbtree.py, with the
one exception being -z/--struct-depth which is lowercase to avoid
conflict with the -Z/--depth used to indicate the filesystem tree depth.

I think this is a surprisingly reasonable way to show the inner
structure of files without clobbering the user's console with file
contents.

Don't worry, if clobbering is desired, -T/--no-truncate still dumps all
of the file content.

Though it's still up to the user to manually apply the sprout/shrub
overlay. That step is still complex enough to not implement in this
tool yet.

I

scripts/dbgmtree.py

@@ -1573,7 +1573,7 @@ def main(disk, mroots=None, *,
                                 for tag, j, d, data in tags
                                 if tag & 0x7f00 != TAG_NAME]
 
-                    # find mdir in the tags
+                    # found an mdir in the tags?
                     mdir__ = None
                     if (not args.get('depth')
                             or mdepth+len(path) < args.get('depth')):
@@ -1582,7 +1582,7 @@ def main(disk, mroots=None, *,
                             if tag == TAG_MDIR),
                             None)
 
-                    # print btree entries in certain cases
+                    # show other btree entries in certain cases
                     if args.get('inner') or not mdir__:
                         dbg_branch(mbid, mw, rbyd, rid, tags, len(path)-1)
 
@@ -1656,10 +1656,6 @@ if __name__ == "__main__":
         '-T', '--no-truncate',
         action='store_true',
         help="Don't truncate, show the full contents.")
-    parser.add_argument(
-        '-i', '--inner',
-        action='store_true',
-        help="Show inner branches.")
     parser.add_argument(
         '-t', '--tree',
         action='store_true',
@@ -1668,6 +1664,10 @@ if __name__ == "__main__":
         '-b', '--btree',
         action='store_true',
         help="Show the underlying B-tree.")
+    parser.add_argument(
+        '-i', '--inner',
+        action='store_true',
+        help="Show inner branches.")
     parser.add_argument(
         '-Z', '--depth',
         nargs='?',