add overview_feature_stack_view option

etc/options

@@ -339,6 +339,11 @@ feature_plot_height = 160
 # overview_one_line_per_entry = yes
 
 
+# if this option is yes then the overview will start showing the feature
+# stack view (the default is no)
+# overview_feature_stack_view = yes
+
+
 # if this option is "yes" then the feature list will be displayed on startup
 # (this is the default)
 show_list = yes