Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 bytestream(Arg1, Arg2)

 bytestream_int(Arg1, Arg2, Arg3)

 read_all_bytes(Arg1, Arg2)

 byte_group(Arg1, Arg2)

 byte_groups(Arg1, Arg2)