'@', unless --expert is set. This is to help prevent people from
polluting the (as yet unused) IETF namespace.
* main.h: Comments about default algorithms.
* photoid.c (image_type_to_string): Comments about 3-letter file
extensions.
FIXED_PHOTO_VIEWER and DISABLE_PHOTO_VIEWER.
* mainproc.c (check_sig_and_print): Use --show-photos to show photos when
verifying a sig made by a key with a photo.
* keyserver.c (parse_keyserver_uri): Properly parse a URI with no :port
section and an empty file path, but with a terminating '/'.
(keyserver_work): Honor DISABLE_KEYSERVER_HELPERS.
* hkp.c (hkp_ask_import): Display keyserver URI as a URI, but only if
verbose.
* exec.c, g10.c: USE_EXEC_PATH -> FIXED_EXEC_PATH
