Isabelle2018: new comment syntax

(result of "isabelle update_comments <dirs>")

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.

x64: crefine: move two lemmas up to CSpaceAcc_C

clib: infrastructure for using AutoCorres in CRefine

x64: clear some sorry proofs from CSpace_C

Also update some Haskell and abstract specs relating to IO ports.

x64 crefine: update scheduler bitmap lemmas

Applied the changes from invert-fastpath on ARM_HYP to available X64
files, updated relevant proofs to 64-bit, reduced IpcCancel sorries to
sign_extend only, reduced Schedule to one sorry.

x64 crefine: added CSpaceAcc_C