[image] Simplify image management

Refactor the {load,exec} image operations as {probe,exec}.  This makes
the probe mechanism cleaner, eliminates some forward declarations,
avoids holding magic state in image->priv, eliminates the possibility
of screwing up between the "load" and "exec" stages, and makes the
documentation simpler since the concept of "loading" (as distinct from
"executing") no longer needs to be explained.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/downloader.c

@@ -218,8 +218,7 @@ static struct interface_descriptor downloader_job_desc =
  * @ret rc		Return status code
  *
  * Instantiates a downloader object to download the specified URI into
- * the specified image object.  If the download is successful, the
- * image registration routine @c register_image() will be called.
+ * the specified image object.
  */
 int create_downloader ( struct interface *job, struct image *image,
 			int type, ... ) {