date-chooser: tweak style

To keep the current date chooser in sync with
GNOME Shell, tweak the week names to show only
the first, upcased letter of the week name.

Also, this commit avoids making day number circles
ellipses when the week number is not present.

src/gcal-date-chooser-day.c

@@ -337,6 +337,9 @@ gcal_date_chooser_day_init (GcalDateChooserDay *self)
 {
   GtkWidget *widget = GTK_WIDGET (self);
 
+  gtk_widget_set_halign (widget, GTK_ALIGN_CENTER);
+  gtk_widget_set_valign (widget, GTK_ALIGN_CENTER);
+
   gtk_widget_set_can_focus (widget, TRUE);
   gtk_style_context_add_class (gtk_widget_get_style_context (widget), "day");
 

src/gcal-date-chooser.c

@@ -205,12 +205,20 @@ static gchar *
 calendar_get_weekday_name (gint i)
 {
   GDateTime *date;
+  gchar *formatted_date;
+  gchar *upcased_date;
   gchar *text;
 
   date = g_date_time_new_local (2015, 1, 4 + i, 1, 1, 1);
-  text = g_date_time_format (date, "%a");
+  formatted_date = g_date_time_format (date, "%a");
   g_date_time_unref (date);
 
+  upcased_date = g_utf8_strup (formatted_date, -1);
+  g_free (formatted_date);
+
+  text = g_utf8_substring (upcased_date, 0, 1);
+  g_free (upcased_date);
+
   return text;
 }