TODO:
can log_file be written to?
add systemd unit?

gmi.pl needs to accept an arguemnt, where the config.toml is located.

remove magic numbers

make log output user adjustable

add client certificate stuff

add gmiaccess stuff

add cgi stuff

better magic detection

check if loaded cert/keys are actually valid

check values for keys in config file

redirection via config

handle signals like interrupt better

reduce complexity in listen_config()