*after* providing input.
In particular if the existing config does not validate then we
should just ensure that the problematic question is displayed
without a confusing error message beforehand; the error should
only appear if the newly entered response doesn't validate.
> Some people, when confronted with a problem, think "I know, I'll use regular expressions."
> Now they have two problems.
Dongle "device index" actually accepts serial numbers too, document that.
/etc/default/dump1090-mutability is now generated in postinst,
if it doesn't exist, from a template in /usr/share/dump1090-mutability.
Subsequently, the config file is updated in place if debconf-driven
changes are made.
Static HTML/javascript have moved to a "html" subdir to avoid exposing
the template via the webserver.
