Remove pure word lemmas from proof/*

Removes redundant lemmas after moving them up to Word_Lib.

Isabelle2018: new "op x" syntax; now is "(x)"

(result of "isabelle update_op -m <dir>")

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: cleared sorries in CSpace_RAB_C

x64: crefine: update sorries for C changes

changes include:
* zombie bit numbers changing
* object sizes abstracted

x64: crefine: added CSpace_RAB_C.thy