Add top_bar option

Possible values:
- never
- no-border: in windowed mode when border is disabled, or fullscreen
- always

Closes #15

README.md

@@ -105,7 +105,9 @@ menu_hjkl_navigation=no
 menu_opacity=0.8
 menu_font_scale=1
 
-# top bar with window controls and media title shown only in no-border mode
+# top bar with window controls and media title
+# can be: never, no-border, always
+top_bar=no-border
 top_bar_size=40
 top_bar_size_fullscreen=46
 top_bar_persistency=