Use Unicode in translatable strings

See https://developer.gnome.org/hig/stable/typography.html

https://bugzilla.gnome.org/show_bug.cgi?id=772218

data/org.gnome.mutter.gschema.xml.in

@@ -6,11 +6,11 @@
       <default>'Super_L'</default>
       <summary>Modifier to use for extended window management operations</summary>
       <description>
-        This key will initiate the "overlay", which is a combination window
+        This key will initiate the “overlay”, which is a combination window
         overview and application launching system.  The default is intended
-        to be the "Windows key" on PC hardware.
+        to be the “Windows key” on PC hardware.
 
-        It's expected that this binding either the default or set to
+        It’s expected that this binding either the default or set to
         the empty string.
       </description>
     </key>
@@ -40,7 +40,7 @@
       <summary>Workspaces are managed dynamically</summary>
       <description>
         Determines whether workspaces are managed dynamically or
-        whether there's a static number of workspaces (determined
+        whether there’s a static number of workspaces (determined
         by the num-workspaces key in org.gnome.desktop.wm.preferences).
       </description>
     </key>
@@ -67,7 +67,7 @@
       <default>false</default>
       <summary>Delay focus changes until the pointer stops moving</summary>
       <description>
-        If set to true, and the focus mode is either "sloppy" or "mouse"
+        If set to true, and the focus mode is either “sloppy” or “mouse”
         then the focus will not be changed immediately when entering a
         window, but only after the pointer stops moving.
       </description>
@@ -78,7 +78,7 @@
       <range min="0" max="64"/>
       <summary>Draggable border width</summary>
       <description>
-          The amount of total draggable borders. If the theme's visible
+          The amount of total draggable borders. If the theme’s visible
           borders are not enough, invisible borders will be added to meet
           this value.
       </description>

src/compositor/compositor.c

@@ -468,7 +468,7 @@ redirect_windows (MetaScreen *screen)
         {
           /* This probably means that a non-WM compositor like xcompmgr is running;
            * we have no way to get it to exit */
-          meta_fatal (_("Another compositing manager is already running on screen %i on display \"%s\"."),
+          meta_fatal (_("Another compositing manager is already running on screen %i on display “%s”."),
                       screen_number, display->name);
         }
 

src/core/display.c

@@ -605,7 +605,7 @@ meta_display_open (void)
 
   if (xdisplay == NULL)
     {
-      meta_warning (_("Failed to open X Window System display '%s'\n"),
+      meta_warning (_("Failed to open X Window System display “%s”\n"),
 		    XDisplayName (NULL));
       return FALSE;
     }

src/core/mutter.c

@@ -37,7 +37,7 @@ print_version (const gchar    *option_name,
   const int latest_year = 2011;
 
   g_print (_("mutter %s\n"
-             "Copyright (C) 2001-%d Havoc Pennington, Red Hat, Inc., and others\n"
+             "Copyright © 2001-%d Havoc Pennington, Red Hat, Inc., and others\n"
              "This is free software; see the source for copying conditions.\n"
              "There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"),
            VERSION, latest_year);

src/core/screen.c

@@ -577,7 +577,7 @@ take_manager_selection (MetaDisplay *display,
         }
       else
         {
-          meta_warning (_("Display \"%s\" already has a window manager; try using the --replace option to replace the current window manager."),
+          meta_warning (_("Display “%s” already has a window manager; try using the --replace option to replace the current window manager."),
                         display->name);
           return None;
         }
@@ -662,7 +662,7 @@ meta_screen_new (MetaDisplay *display,
    */
   if (xroot == None)
     {
-      meta_warning (_("Screen %d on display '%s' is invalid\n"),
+      meta_warning (_("Screen %d on display “%s” is invalid\n"),
                     number, display->name);
       return NULL;
     }

src/x11/session.c

@@ -1812,7 +1812,7 @@ warn_about_lame_clients_and_finish_interact (gboolean shutdown)
   g_slist_free (lame);
 
   pid = meta_show_dialog("--list",
-                         _("These windows do not support "save current setup" "
+                         _("These windows do not support “save current setup” "
                            "and will have to be restarted manually next time "
                            "you log in."),
                          "240",