Make text-quoting-style customizable. Introduce t and new meaning for nil.

A value of nil for text-quoting-style now means "no translation".  t means
"Use curved quotes if displayable".

* src/doc.c (text-quoting-style (function)): modify for new semantics.
(text-quoting-style (variable)): Amend the doc string, set the default value
to t.

* lisp/cus-start.el: (top level): Create a customize entry for
text-quoting-style in group display.

* etc/NEWS: Amend the entry for text-quoting-style.

* doc/emacs/display.texi (Text Display): Describe the translation of ASCII
quotes to curved quotes, and how to influence or inhibit it.

* doc/lispref/control.texi (Signalling Errors)
* doc/lispref/display.texi (Displaying Messages)
* doc/lispref/strings.texi (Formatting Strings): Describe binding
text-quoting-style to nil to inhibit unwanted quote translation.

* doc/lispref/help.texi (Keys in Documentation): Change text-quoting-style
from a variable to a user option.  Describe its changed set of values.  State
that it can be customized freely.

1 files changed, 9 insertions, 0 deletions

diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index fd015b70ca3..f5e1431f6bb 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -223,6 +223,15 @@ Leaving \"Default\" unchecked is equivalent with specifying a default of
              (visible-bell display boolean)
              (no-redraw-on-reenter display boolean)
 
+             ;; doc.c
+             (text-quoting-style display
+                                 (choice
+                                  (const :tag "No translation" nil)
+                                  (const :tag "Prefer \\=‘curved\\=’ quotes, if possible" t)
+                                  (const :tag "\\=‘Curved\\=’ quotes" curved)
+                                  (const :tag "\\='Straight\\=' quotes" straight)
+                                  (const :tag "\\=`Grave\\=' quotes" grave)))
+
              ;; dosfns.c
              (dos-display-scancodes display boolean)
              (dos-hyper-key keyboard integer)