Deleted hex functions, moved to Nettle's

base16 files.
(struct sexp_output): Represent the current encoding as a
nettle_armor pointer and a state struct.
(sexp_output_init): Deleted MODE argument. Now passed to functions
that need it.
(sexp_get_char): Updated to new base64 conventions.
(sexp_get_base64_string): Likewise.
(sexp_put_raw_char): New function.
(sexp_put_newline): Use sexp_put_raw_char.
(sexp_put_char): Use nettle_armor interface for encoding data.
Use OUTPUT->coding_indent for line breaking, so the INDENT
argument was deleted.
(sexp_put_code_start): New function, replacing sexp_put_base64_start.
(sexp_put_code_end): New function, replacing sexp_put_base64_end.
(sexp_put_data): Deleted argument INDENT.
(sexp_puts): Likewise.
(sexp_put_length): Likewise.
(sexp_put_list_start): Likewise.
(sexp_put_list_end): Likewise.
(sexp_put_display_start): Likewise.
(sexp_put_display_end): Likewise.
(sexp_put_string): Likewise. Also changed base64 handling.
(sexp_convert_string): Deleted argument INDENT. New argument
MODE_OUT.
(sexp_convert_list): New argument MODE_OUT.
(sexp_convert_file): Likewise.
(sexp_convert_item): Likewise. Also handle output in transport
mode.
(match_argument): Simple string comparison.
(main): Adapted to above changes.

Rev: src/nettle/examples/sexp-conv.c:1.10