Treat ' like ’ even when not matching `

This is simpler and easier to explain, and should encourage better
typography.  Do this in Electric Quote mode and when translating
quotes in docstrings.  Inspired by a suggestion by Dmitry Gutov	in:
https://lists.gnu.org/archive/html/emacs-devel/2015-08/msg00806.html
* doc/emacs/text.texi (Quotation Marks):
* doc/lispref/help.texi (Keys in Documentation):
* etc/NEWS:
Document this.
* lisp/electric.el (electric-quote-post-self-insert-function):
* src/doc.c (Fsubstitute_command_keys):
Always treat ' like ’ even when not matched by an open quote.

1 files changed, 4 insertions, 16 deletions

diff --git a/doc/lispref/help.texi b/doc/lispref/help.texi
index ab884f8dc80..44c09a2085a 100644
--- a/doc/lispref/help.texi
+++ b/doc/lispref/help.texi
@@ -318,25 +318,13 @@ stands for no text itself.  It is used only for a side effect: it
 specifies @var{mapvar}'s value as the keymap for any following
 @samp{\[@var{command}]} sequences in this documentation string.
 
-@item `
-(grave accent) stands for a left quote, and alters the interpretation
-of the next unmatched apostrophe.
-
-@item '
-(apostrophe) stands for a right quote if preceded by grave accent and
-there are no intervening apostrophes.  Otherwise, apostrophe stands
-for itself.
-
 @item ‘
-(left single quotation mark) stands for a left quote.
+@itemx `
+(left single quotation mark and grave accent) both stand for a left quote.
 
 @item ’
-(right single quotation mark) stands for a right quote.
-
-@item '
-(apostrophe) stands for a right quote if
-preceded by grave accent and there are no intervening apostrophes.
-Otherwise, apostrophe stands for itself.
+@itemx '
+(right single quotation mark and apostrophe) both stand for a right quote.
 
 @item \=
 quotes the following character and is discarded; thus, @samp{\=`} puts