C-x 8 shorthands for curved quotes, Euro, etc.

Although C-x 8 lets you insert arbitrary Unicode characters,
it's awkward to use this to insert commonly used symbols such as curved
quotes, the Euro symbol, etc.  This patch adds simpler sequences for
characters commonly found in English text and in basic math.
For example, assuming the Alt key works on your keyboard and iso-transl
is loaded, one can now type "A-[" instead of "A-RET LEFT SIN TAB RET"
to get the character "‘" (U+2018 LEFT SINGLE QUOTATION MARK).
(Bug#20499)
* doc/emacs/mule.texi (Unibyte Mode):
A few other printing characters now work too.
* etc/NEWS: Document this.
* lisp/international/iso-transl.el (iso-transl-char-map):
Also support the following characters:
‐ ‑ ‒ – — ― ‘ ’ “ ” † ‡ • ′ ″ € № ← → ↔ − ≈ ≠ ≤ ≥

doc/emacs/mule.texi

@@ -1660,8 +1660,8 @@ characters present directly on the keyboard or using @key{Compose} or
 @cindex compose character
 @cindex dead character
 @item
-For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose
-character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing
+You can use the key @kbd{C-x 8} as a ``compose character'' prefix for
+entry of non-@acronym{ASCII} Latin-1 and a few other printing
 characters.  @kbd{C-x 8} is good for insertion (in the minibuffer as
 well as other buffers), for searching, and in any other context where
 a key sequence is allowed.

etc/NEWS

@@ -213,6 +213,9 @@ successive char insertions.
 
 ** Unicode names entered via C-x 8 RET now use substring completion by default.
 
+** C-x 8 now has shorthands for these chars: ‐ ‑ ‒ – — ― ‘ ’ “ ” † ‡ • ′ ″
+€ № ← → ↔ − ≈ ≠ ≤ ≥.  As before, you can type C-x 8 C-h to list shorthands.
+
 ** New minor mode global-eldoc-mode is enabled by default.
 
 ** Emacs now supports "bracketed paste mode" when running on a terminal

lisp/international/iso-transl.el

@@ -1,4 +1,4 @@
-;;; iso-transl.el --- keyboard input definitions for ISO 8859-1  -*- coding: utf-8 -*-
+;;; iso-transl.el --- keyboard input for ISO 10646 chars -*- coding: utf-8 -*-
 
 ;; Copyright (C) 1987, 1993-1999, 2001-2015 Free Software Foundation,
 ;; Inc.
@@ -36,6 +36,10 @@
 ;; to make all of the Alt keys autoload, and it is not clear
 ;; that the dead accent keys SHOULD autoload this package.
 
+;; This package supports all characters defined by ISO 8859-1, along
+;; with a few other ISO 10646 characters commonly used in English and
+;; basic math.
+
 ;;; Code:
 
 ;;; Provide some binding for startup:
@@ -192,6 +196,31 @@
     ("~o"   . [?õ])
     ("~t"   . [?þ])
     ("~~"   . [?¬])
+    ("_h"   . [?‐])
+    ("_H"   . [?‑])
+    ("_f"   . [?‒])
+    ("_n"   . [?–])
+    ("_m"   . [?—])
+    ("_q"   . [?―])
+    ("["    . [?‘])
+    ("]"    . [?’])
+    ("{"    . [?“])
+    ("}"    . [?”])
+    ("1+"   . [?†])
+    ("2+"   . [?‡])
+    ("**"   . [?•])
+    ("*'"   . [?′])
+    ("*\""  . [?″])
+    ("*E"   . [?€])
+    ("No"   . [?№])
+    ("a<"   . [?←])
+    ("a>"   . [?→])
+    ("a="   . [?↔])
+    ("_-"   . [?−])
+    ("~="   . [?≈])
+    ("/="   . [?≠])
+    ("_<"   . [?≤])
+    ("_>"   . [?≥])
     ("' "   . "'")
     ("` "   . "`")
     ("\" "  . "\"")