Sets the parent of self to e

Property definitions

dom $ XMLEntity :: parent=
	# Sets the parent of `self` to `e`
	fun parent=(e: XMLEntity) do
		var parent = self.parent
		if parent != null then
			parent.children.remove(self)
		end
		e.children.add(self)
	end
lib/dom/xml_entities.nit:47,2--54,4