Merged with dev

CMakeLists.txt

assets/materials/subsurfaceScatter.yml

assets/models/Dragon.yml

assets/models/cube.yml

assets/models/spaceSkybox.yml

assets/scenes/demo1.yml

include/overkill/ModelSystem.hpp

include/overkill/Parser.hpp

include/overkill/ShaderSystem.hpp

include/overkill/TextureSystem.hpp

src/EntityDirectionalLight.cpp

src/EntityPointLight.cpp

src/Init.cpp

src/MaterialSystem.cpp

src/ModelSystem.cpp

src/Parser.cpp

src/Scene.cpp

src/ShaderSystem.cpp

src/TextureSystem.cpp

src/Util.cpp