Adjust use of ellipsis (...) in menus according to Gnome HIG (#2035)

* Adjust use of ellipses (...) in menus according to Gnome HIG

https://developer.gnome.org/hig/stable/writing-style.html.en

src/common/hexchat.c

@@ -883,9 +883,9 @@ xchat_init (void)
 		"NAME ENDSUB\n"				"CMD \n\n",
 
 		_("_Open Dialog Window"), "gtk-go-up",
-		_("_Send a File"), "gtk-floppy",
+		_("_Send a File" ELLIPSIS), "gtk-floppy",
 		_("_User Info (WhoIs)"), "gtk-info",
-		_("_Add to Friends List"), "gtk-add",
+		_("_Add to Friends List" ELLIPSIS), "gtk-add",
 		_("_Ignore"), "gtk-stop",
 		_("O_perator Actions"),
 

src/common/util.h

@@ -35,6 +35,8 @@
 
 #define rfc_tolower(c) (rfc_tolowertab[(unsigned char)(c)])
 
+#define ELLIPSIS "\xe2\x80\xa6"
+
 extern const unsigned char rfc_tolowertab[];
 
 char *expand_homedir (char *file);