/*
 * Save an Imlib2::Image to a file (no exception or error).
 * 
 * Provides access to the low-level imlib_save_image() call.  You
 * probably want to use Imlib2::Image::save() instead.
 *
 * Examples:
 *   image.save_image 'output_file.png'
 *
 */
static VALUE image_save_image(VALUE self, VALUE val) {