boolify functions, params, variables

boolify functions, params, variables

- add_folder()
- body_to_data_object()
- browse_add_list_result()
- check_certificate_file()
- crypt_id_is_strong()
- imap_check()
- imap_check_mailbox()
- imap_exec_msgset()
- imap_mailbox_check()
- imap_status()
- imap_sync_mailbox()
- index_format_str()
- init_menu()
- interactive_check_cert()
- msg_search()
- mutt_enter_string_full()
- mutt_get_field_full()
- mutt_num_postponed()
- mutt_sort_headers()
- pgp_check_traditional_one_body()
- print_ref()
- set_copy_flags()
- set_noconv_flags()