show_notation): Collapse the old print_notation_data into show_policy()
and show_notation() so there is only one function to print notations and
policy URLs.
* options.h, main.h, g10.c (main), keyedit.c (print_and_check_one_sig),
keylist.c (list_one, list_keyblock_print), pkclist.c (do_edit_ownertrust),
sign.c (mk_notation_and_policy): New "list-options" and "verify-options"
commands. These replace the existing --show-photos/--no-show-photos,
--show-notation/--no-show-notation,
--show-policy-url/--no-show-policy-url, and --show-keyring options. The
new method is more flexible since a user can specify (for example) showing
photos during sig verification, but not in key listings. The old options
are emulated.