Node Dir -> Scene; Scene Class

Node directory changed to Scene to reflect what they are related to
(the scene/scene graph).

Scene Class handles nodes of the Scene Graph. Loads scenes from file.

Materials - load from aiMaterial
SceneNode - name (std::string)
Merge branch 'master' of https://github.com/gingerBill/Ludum

Conflicts:
	game
	include/Ludum/Scene/Scene.hpp
	src/Ludum/Scene/Scene.cpp
	src/Ludum/World/World.cpp