/*
 * Copy a rectangle to the specified coordinates
 *
 * Examples:
 *   x, y, w, h = 10, 20, 100, 200
 *   dest_x, dest_y = 5, 10
 *   image.copy_rect x, y, w, h, dest_x, dest_y
 *
 *   source_rect = [10, 20, 100, 200]
 *   dest_coords = [5, 10]
 *   image.copy_rect source_rect, dest_coords
 *
 *   values = [10, 20, 100, 200, 5, 10]
 *   image.copy_rect values
 *
 */
static VALUE image_copy_rect(int argc, VALUE *argv, VALUE self) {