Implement PixelRegion option for imread(). * imread.m: document new option. * private/__imread__.m: parse new option and set defaults. * __magick_read__.cc (calculate region): new option to calculate the region to be read, shifts in memory required, and output image size. (read_indexed_images, read_images): implement reading of only specific regions of an image. (__magick_read__): get octave_scalar_map at start for simplicity.

#include <iostream>
#include <octave/oct.h>

int
main (void)
{
  std::cout << "Hello Octave world!\n";

  int n = 2;
  Matrix a_matrix = Matrix (n, n);

  for (octave_idx_type i = 0; i < n; i++)
    for (octave_idx_type j = 0; j < n; j++)
      a_matrix(i,j) = (i + 1) * 10 + (j + 1);

  std::cout << a_matrix;

  return 0;
}