Image Header:
  0: Format version
  1: Endianness
  1: Header size
  2: Size of memory
  3: Start of memory
  4: SpecialObjectsOop
  5: Last identity-hash value
  6: Extra VM memory (?)

Provisional image header (offsets in bytes, all fields endian dependent) -
  0: magic number, set to 16rABCDEF42 (endian dependent order). 
    If image is little endian, low byte will be 42.
    If image is big endian, high byte will be 42.
  4: size of the image
  8: the next identity hash to assign
  12: the special objects oop, as a displacement from the start of the image
  16: start of the image
  ...
  16+N-1: last byte of image, where N is the size of the image