* 'plb human2quittee' doesn't exit on '+++'

* plb human2sink and plb human2quittee echo input, I think it should not

* do I need to reintroduce the custom message display function? (it's probably only when
  I try raw mode that I'm going to know)

* write an echo task and get it to work with human and a "inverse echo" that writes and
  then reads (and discards).

* write a human-->echo-->sink model

* write a stupid cli that just echos back what I type and try out.

* write a quitter program that sends several outputs, the middle one of which is the quit
  code '+++' and write a model to connect quitter to quittee. I want to see it being
  killed of early, I think.

* can I revisit the cli() thread now?

* add stupid commands to launch the built in threads (my_clock, my_sink, my_quitter)

* make the relayer capable of relaying more than one connection