Description of a series of bytes.

A "bytes" is a metadata (JSON) blob to describe blobs.  It's a recursive
definition that's able to describe a hash tree, describing very large
blobs (or "files").

A "bytes" blob can be used on its own, but is also used by things like
a "file" schema blob.


{"camliVersion": 1,
 "camliType": "bytes",

  // Required.  Array of contiguous regions of bytes.  Zero or more elements.
  //
  // Each element must have:
  //    "size": the number of bytes that this element contributes to array of bytes.
  //            Required, and must be greater than zero.
  //
  // At most one of:
  //    "blobRef": where to get the raw bytes from.  if this and "bytesRef"
  //               are missing, the bytes are all zero (e.g. a sparse file hole)
  //    "bytesRef": alternative to blobRef, where to get the range's bytes
  //                from, but pointing recursively at a "bytes" schema blob
  //                describing the range, recursively. large files are made of
  //                these in a hash tree.  it is an error if both "bytesRef"
  //                and "blobRef" are specified.
  //
  // Optional:
  //    "offset": the number of bytes into blobRef or bytesRef to skip to
  //              get the necessary bytes for the range. usually zero (unspecified)
  "parts": [
    {"blobRef": "digalg-blobref", "size": 1024},
    {"bytesRef": "digalg-blobref", "size": 5000000, "offset": 492 },
    {"size": 1000000},
    {"blobRef": "digalg-blobref", "size": 10},
   ]
}