Active menu item

Depends on the current page, this allows to hilighted the current item.

Property definitions

nitc $ DocTopMenu :: active_item
	# Active menu item
	#
	# Depends on the current page, this allows to hilighted the current item.
	var active_item: nullable ListItem is noinit, writable
src/doc/static/static_html.nit:281,2--284,55