While in hex mode (ctrl-t h) you can output hexadecimal values.
E.g.: to send 0x0A you have to type 0A (always 2 characters).
Added option -x, --hex to start in hexadecimal mode.
Added option --newline-in-hex to interpret newline characters in hex mode.
This is disabled by default, because, in my opinion, hex stream is
fundamentally different from text, so a "new line" is meaningless in this
context.