Util.cpp, namespace overkill everywhere and loading material file

CMakeLists.txt

assets/materials/brick.yml

include/overkill/Material.hpp

include/overkill/Model.hpp

include/overkill/Parser.hpp

include/overkill/ShaderProgram.hpp

include/overkill/Util.hpp

include/overkill/elementBuffer.hpp

include/overkill/renderer.hpp

include/overkill/texture.hpp

include/overkill/vertexArray.hpp

include/overkill/vertexBuffer.hpp

include/overkill/vertexBufferAttribLayout.hpp

src/Material.cpp

src/MaterialSystem.cpp

src/Model.cpp

src/Parser.cpp

src/ShaderProgram.cpp

src/TextureSystem.cpp

src/Util.cpp