Support the component chain syntax (as the UnityEngine style):

	ComponentHandle<C>::entity();
	ComponentHandle<C>::component<C1>();
	ComponentHandle<C>::has_component<C1>();

	Component<C>::entity();
	Component<C>::component<C1>();
	Component<C>::has_component<C1>();
Merge branch 'master' of https://github.com/x-w/entityx