The `while` keyword

Property definitions

	# The `while` keyword
	var n_kwwhile:  TKwwhile is writable, noinit

src/parser/parser_nodes.nit:2008,2--2009,45

	redef fun n_kwwhile=(node)
	do
		_n_kwwhile = node
		node.parent = self
	end

src/parser/parser_prod.nit:3251,2--3255,4