Add :results output option

[michaelkpfeifer]

Adding a ":results output" option suppresses the output of the respective computation in IEx. This allows to use IO.puts/2 or IO.inspect/2 without displaying the result of the computation.

Compare

      #+BEGIN_SRC elixir :results output
        IO.inspect List.to_string('hello')
        IO.inspect String.to_charlist("hello")
      #+END_SRC

      #+RESULTS:
      : "hello"
      : 'hello'

to

      #+BEGIN_SRC elixir
        IO.inspect List.to_string('hello')
        IO.inspect String.to_charlist("hello")
      #+END_SRC

      #+RESULTS:
      : "hello"
      : 'hello'
      : 'hello'