v0.7.4: Added gonbui.RequestInput

Just in case. It can be handy where a password/key needs to be typed for instance, and one doesn't want to leave traces of it in the notebook. Or for educational purposes.

• Issue #38:
  • %with_inputs and %with_password now wait 200 milliseconds each time (a constant), before
    prompting user with an input in the Jupyter Notebook.
  • Added gonbui.RequestInput, that will prompt the user with a text field in the notebook.