More cl doc updates

More cl doc updates

* doc/misc/cl.texi: Don't mess with the TeX section number counter.
Use Texinfo recommended convention for quotes+punctuation.
(Overview, Sequence Functions): Rephrase for better line-breaking.
(Time of Evaluation, Type Predicates, Modify Macros, Function Bindings)
(Macro Bindings, Conditionals, Iteration, Loop Basics)
(Random Numbers, Mapping over Sequences, Structures)
(Porting Common Lisp): Further updates for cl-lib namespace.
(Modify Macros, Declarations, Macro Bindings, Structures):
Break long lines in examples.
(Dynamic Bindings): Update for changed progv behavior.
(Loop Examples, Efficiency Concerns): Markup fixes.
(Structures): Remove TeX margin change.

* lisp/emacs-lisp/cl-macs.el (cl-progv): Doc fix.

* etc/NEWS: Related markup.