lib: A tutorial and some 'modify' monad rules for Lib.EquivValid

Thanks to Toby Murray (@tobycmurray) for early feedback.

Signed-off-by: Robert Sison <robert.sison@unimelb.edu.au>

licenses: convert license tags to SPDX

lib: bump LibTests timeout to 1800s

Isabelle2018: record c-parser dependency for LibTest

A clean build complains about the generated grammar files missing from the C
parser even if the session itself does not depend on the CParser session.

lib: add Lib test sessions

lib: make Lib session a test dependency

Also ensure that the C parser is built before Lib, because it depends
on generated grammar files that need `make'.