Unable to use escape characters

I would like to be able to use e.g. \x16 to mean the ASCII character SYN (position 0x16). So I would like to use \xhh in string literals to pick any ASCII character. I would also like to be able to write \n as alias for \x0a which is newline.

Cf. https://tezos.stackexchange.com/questions/2858/can-i-use-escape-characters-in-ligo-strings