Change some keyedit functions to allow printing to arbitrary streams.
* common/ttyio.c (tty_print_string): Add optional arg FP. Change all callers. (tty_print_utf8_string2): Ditto. * g10/keyedit.c (show_prefs): Ditto. (show_key_with_all_names_colon): Ditto. (show_names): Ditto. * g10/keylist.c (print_revokers): Ditto. (print_fingerprint): Ditto.