Improve group count readability

It is hard to read on black panels with bright/light icons

I suggest adding the following in Themes.h:

#define DEFAULT_THEME ".menu { margin: 0; padding: 0; border: 0; background-color: @menu_bgcolor; }\n" \
+					  ".window_count { text-shadow: 2px 2px 2px black; color: white;  }\n" \
					  ".hover_menu_item { background-color: alpha(@menu_item_color_hover, 0.2); }\n";

I would prefer a proper Outline, but i couldn't figure out how to do it with gtk