#5 AMIS should start with no open book

[Marisa DeMeglio]

Make a mode of AMIS in which no book is open.

I think the request for such a feature come from users
who are having problems with CD-loading/book switching,
and they want to close a book before opening a new one
because they think this will cause fewer errors. (I
don't think so but evaluation of many of these errors
is pending receiving test content)

Technically, this situation (no book loaded) could also
happen if the default start book is not found and the
most recent book is not found. Although, this should
point to a problem in the configuration of AMIS
(missing help book!)