Implement IPython input message

[Doug Blank]

When talking to a Calico language, input() should be able to open up area in notebook/console for entering data, and send it to kernel. That way, we don't have to have GUI enabled.

(When this is completed, we can also set input() remapping to only be necessary when under gtk gui).

[Doug Blank]

Fixes #158: Implement IPython input message, as calico.input(prompt)

→ <<cset a562bd62ee96>>