[gtkmm] Book update status

[murrayc t-online de (Murray Cumming)]

I am slowly but surely updating the "Programming with gtkmm" book.
Everything up to then end of Chapter 7's "Single-item containers"
section should be up-to-date.
http://www.gtkmm.org/gtkmm2/docs/tutorial/html/index.html

In particular, now that our reference documentation is so much better, I
have chosen not to duplicate that information in the book. Instead, the
book now contains links to relevant parts of the reference
documentation. This reduces the text considerably, which I think is a
good thing.

The example code is now just linked to, but we might do some processing
later to show it inline.

I am also including screenshots of all the examples, and rewriting the
examples as I update those sections. The updated examples are in
examples/book.

-- 
Murray Cumming
murray usa net
www.murrayc.com