Fix bug #19136 with a typo in a vc.el comment.

 lisp/vc/vc.el: Fix a typo in the commentary.
Fix the build of the Emacs User manual.

 doc/emacs/maintaining.texi (Version Control Systems): Move "@end itemize"
 past the last @item.  Fix a typo (reported by H. Dieter Wilhelm
 <dieter@duenenhof-wilhelm.de>).
Fix bug #1702 with missing feature in arc-mode.el.

 lisp/arc-mode.el (archive-visit-single-files): New.
 (archive-mode): Visit file if archive contains a single file.
Fix bug #19084 with 'C-x v +' in *vc-change-log* buffers.

 lisp/vc/vc.el (vc-deduce-fileset): Support invocation from
 *vc-change-log* buffer.
Fix bug that produced spurious nil state.
'libxml-parse(html|xml)-region': new optional param 'discard-comments'.

* doc/lispref/text.texi (Parsing HTML/XML): Document new optional parameter
'discard-comments' of 'libxml-parse(html|xml)-region'.

* src/xml.c (parse_region): Take care of new optional parameter
'discard-comments' of 'libxml-parse(html|xml)-region'.
(Flibxml_parse_html_region, Flibxml_parse_xml_region): New
optional parameter 'discard-comments'.

* test/automated/libxml-tests.el
(libxml-tests--data-comments-preserved): Renamed from
'libxml-tests--data'.
(libxml-tests--data-comments-discarded): New.
(libxml-tests): Check whether 'libxml-parse-xml-region' is
discarding comments correctly.
Ignore files and fix indentation of else static if in d-mode
Emacs compiles after porting changes from http://cx4a.org/repo/emacs.bzr/regexp
Add flag compilation-do-echo-command
Ignore nil variables in c-backward-over-enum-header() in cc-engine.el
Ignore nil variables in c-looking-at-decl-block() in cc-engine.el