paragraphs: recognise more Unicode characters as end of sentence

* lisp/textmodes/paragraphs.el (sentence-end-base): Include an
ellipsis (…) and interrobang (‽) characters as end of a sentence,
and a closing single quote (’) as an end of a quote.

lisp/ChangeLog

+2015-01-20  Michal Nazarewicz  <mina86@mina86.com>
+
+	* textmodes/paragraphs.el (sentence-end-base): Include an
+	ellipsis (…) and interrobang (‽) characters as end of a sentence,
+	and a closing single quote (’) as an end of a quote.
+
 2015-01-20  Michal Nazarewicz  <mina86@mina86.com>
 
 	* textmodes/tildify.el (tildify-double-space-undos): A new

lisp/textmodes/paragraphs.el

@@ -168,7 +168,7 @@ to obtain the value of this variable."
   :type '(choice regexp (const :tag "Use default value" nil)))
 (put 'sentence-end 'safe-local-variable 'string-or-null-p)
 
-(defcustom sentence-end-base "[.?!][]\"'”)}]*"
+(defcustom sentence-end-base "[.?!…‽][]\"'”’)}]*"
   "Regexp matching the basic end of a sentence, not including following space."
   :group 'paragraphs
   :type 'string