KaitaiStream must have ability to report position relative to root IO object

[Mingun]

That absolute positions must be stored in the debug maps (_attrStart, _attrEnd, _arrStart, _arrEnd). Without that it is impossible or too hard to determine correct position of parsed objects, especially of instances objects.

For example, consider following KSY:

meta:
  id: offsets
seq:
  - id: padding
    type: u1
  - id: unsized
    type: type
  - id: sized
    type: type
    size: 10
types:
  type:
    seq:
      - id: padding
        type: u1
      - id: unsized_simple
        type: u1
      - id: sized_simple
        size: 1
      - id: unsized_array
        type: elem
        repeat: expr
        repeat-expr: 2
      - id: sized_array
        type: elem
        size: 3
        repeat: expr
        repeat-expr: 1
  elem:
    seq:
      - id: padding
        type: u1
      - id: value
        type: u1

The following problem is currently being observed:
This show correct location

That location is wrong, must be inside previous region: