Bug#191079: cdebconf-newt-udeb: visual indication of question/information type

[Petter Reinholdtsen <pere@hungry.com>]

Package: cdebconf-newt-udeb
Version: 0.36

A first time user of d-i told me that it was confusing when something
went wrong with the installation.  The error messages did not visually
stand out from the normal question and information dialogs.

I suggest adding a way to indicate if the user interaction is
information only, a warning, or an error situation.

We chould add 'ERROR:', 'Warning:' and 'Info:' to the title, or
perhaps use different colors or icons to indicate this.

Asking about the language and reporting that kernel-installer failed
should be visually different to make sure the user know he should take
the latter dialog more serious.

I believe this is an important usability issue for d-i.