Optionally even widths of `display-buffer' windows.  (Bug#21100)

* lisp/window.el (quit-restore-window): Restore width if
requested.
(display-buffer-record-window): Record width when window is
reused and horizontally combined.
(even-window-sizes): New option to allow evening window widths.
(even-window-heights): Defalias to `even-window-sizes'.
(window--even-window-heights): Rename to
`window--even-window-sizes'.  Handle side-by-side windows.
(display-buffer-use-some-window): Call `window--even-window-sizes'
instead of `window--even-window-heights'.
* lisp/help.el (resize-temp-buffer-window): Fix indentation.

* doc/lispref/windows.texi (Choosing Window Options): Describe
`even-window-sizes'.
(Coordinates and Windows): Fix typo.

* etc/NEWS:
* doc/lispref/frames.texi (Mouse Tracking): Document the special
effect of setting 'track-mouse' to 'dragging'.

* lisp/textmodes/artist.el (artist-mouse-draw-continously):
* lisp/ruler-mode.el (ruler-mode-mouse-drag-any-column-iteration):
* lisp/mouse-drag.el (mouse-drag-throw):
* lisp/mouse.el (mouse-drag-line): Set 'track-mouse' to 'dragging'
to avoid changes in the shape of the mouse pointer.

* src/xdisp.c (define_frame_cursor1): Don't change the mouse
pointer shape when do_mouse_tracking has the value of 'dragging',
not just any non-nil value.  (Bug#20934)
(syms_of_xdisp): DEFSYM 'dragging'.

(Bug#20924)

* doc/lispref/nonascii.texi (Character Properties): Correct
inaccuracies in description of values of the Unicode properties.

* doc/lispref/help.texi (Keys in Documentation):
* lisp/international/mule-cmds.el (set-locale-environment):
* lisp/term/w32console.el (terminal-init-w32console):
* src/doc.c (Fsubstitute_command_keys, Vhelp_quote_translation):
If ‘ is not displayable, transliterate it to `, not to '.  See:
http://lists.gnu.org/archive/html/emacs-devel/2015-06/msg00542.html

Fix several problems with the recently-added custom variable
help-quote-translation where the code would quote inconsistently
in help buffers.  Add support for quoting 'like this', which
is common in other GNU programs in ASCII environments.  Change
help-quote-translation to use more mnemonic values: values are now the
initial quoting char, e.g., (setq help-quote-translation ?`) gets the
traditional Emacs help-buffer quoting style `like this'.  Change the
default behavior of substitute-command-keys to match what's done in
set-locale-environment, i.e., quote ‘like this’ if displayable,
'like this' otherwise.
* doc/lispref/help.texi (Keys in Documentation): Document
new behavior of substitute-command-keys, and document
help-quote-translation.
* doc/lispref/tips.texi (Documentation Tips):
Mention the effect of help-quote-translation.
* etc/NEWS: Mention new behavior of substitute-command-keys,
and merge help-quote-translation news into it.
When talking about doc strings, mention new ways to type quotes.
* lisp/cedet/mode-local.el (overload-docstring-extension):
Revert my recent change to this function, which shouldn't be
needed as the result is a doc string.
* lisp/cedet/mode-local.el (mode-local-print-binding)
(mode-local-describe-bindings-2):
* lisp/cedet/srecode/srt-mode.el (srecode-macro-help):
* lisp/cus-theme.el (describe-theme-1):
* lisp/descr-text.el (describe-text-properties-1, describe-char):
* lisp/emacs-lisp/cl-generic.el (cl--generic-describe):
* lisp/emacs-lisp/eieio-opt.el (eieio-help-class)
(eieio-help-constructor):
* lisp/emacs-lisp/package.el (describe-package-1):
* lisp/faces.el (describe-face):
* lisp/help-fns.el (help-fns--key-bindings)
(help-fns--compiler-macro, help-fns--parent-mode)
(help-fns--obsolete, help-fns--interactive-only)
(describe-function-1, describe-variable):
* lisp/help.el (describe-mode):
Use substitute-command-keys to ensure a more-consistent quoting
style in help buffers.
* lisp/cus-start.el (standard):
Document new help-quote-translation behavior.
* lisp/emacs-lisp/lisp-mode.el (lisp-fdefs):
* lisp/help-mode.el (help-xref-symbol-regexp, help-xref-info-regexp)
(help-xref-url-regexp):
* lisp/international/mule-cmds.el (help-xref-mule-regexp-template):
* lisp/wid-edit.el (widget-documentation-link-regexp):
Also match 'foo', in case we're in a help buffer generated when
help-quote-translation is ?'.
* src/doc.c: Include disptab.h, for DISP_CHAR_VECTOR.
(LEFT_SINGLE_QUOTATION_MARK, uLSQM0, uLSQM1, uLSQM2, uRSQM0)
(uRSQM1, uRSQM2, LSQM, RSQM): New constants.
(Fsubstitute_command_keys): Document and implement new behavior.
(Vhelp_quote_translation): Document new behavior.

* doc/emacs/basic.texi (Inserting Text):
Mention C-x 8.  Change example to use curved quote rather
than infinity, as this lets us give more ways to do it.
* doc/emacs/mule.texi (International Chars): Mention C-x 8 shortcuts
and quotation marks.
* doc/emacs/text.texi (Quotation Marks):
* doc/lispref/tips.texi (Documentation Tips):
Add "curly quotes" and "curved quotes" to the index.
* doc/emacs/text.texi (Quotation Marks):
Give the C-x 8 shorthands for curved quotes.
Cross-reference to "Quotation Marks".

* doc/lispref/display.texi (Fontsets): Say explicitly that
CHARACTER can be a single codepoint.
* src/fontset.c (Fset_fontset_font): Doc fix.

* src/font.c (Ffont_spec): Doc fix: elaborate on the values and
use of the ':lang' property of the font spec.
* doc/emacs/frames.texi (Fonts): Document the language names that
can be in the STYLE part of XLFD.
* doc/lispref/display.texi (Low-Level Font): Document the ':lang'
property.