autocorres: fix code inclusion in quickstart doc

The AutoCorres quickstart document includes code from `*.c` files from a
given line number, to avoid including license headers and other details
that aren't useful in the document. This updates the line numbers for
the current license headers.

Signed-off-by: Matthew Brecknell <Matthew.Brecknell@data61.csiro.au>

licenses: convert license tags to SPDX

autocorres: update cartouches for Isabelle2019

Isabelle2018: AutoCorresDoc

globally use session-qualified imports; add Lib session

Session-qualified imports will be required for Isabelle2018 and help clarify
the structure of sessions in the build tree.

This commit mainly adds a new set of sessions for lib/, including a Lib
session that includes most theories in lib/ and a few separate sessions for
parts that have dependencies beyond CParser or are separate AFP sessions.
The group "lib" collects all lib/ sessions.

As a consequence, other theories should use lib/ theories by session name,
not by path, which in turns means spec and proof sessions should also refer
to each other by session name, not path, to avoid duplicate theory errors in
theory merges later.

autocorres: fix C source formatting in quickstart doc

autocorres: NICTA URLs -> D61 URLs

autocorres: Tweak quickstart documentation.

Get ready to publish to the website.

Import release snapshot.