Sets boolean to prevent user intervention. This is the same as setting Vedeu::Config::API#interactive to false.

# Set:
Vedeu.configure do
  standalone! # Same as `standalone true` or `interactive false`.
  # ...
end

Vedeu.configure do
  standalone true # Disallow user input.
  # ...
end

Vedeu.configure do
  standalone false # Allow user input.
  # ...
end

# Get:
Vedeu.config.standalone