Re-order the JPEG quantization tables to normal order when
loading. This wastes a few CPU cycles if you don't need them.
But it has the advantage of hiding the zigzag order JPEG
implementation detail of these tables completely from Pillow
users.

This difference has led to cases where:
* arrays in zigzag order were taken from a dict and passed
  directly as a qtables parameter, causing them to be "zigzagged"
  again by libjpeg.
* dicts with lists in normal order being passed to
  JpegImagePlugin.convert_dict_qtables, causing them to be
  unnecessarily "de-zigzagged".