INT: back to basic shader to test diffuse color from mtl file
INT: phong shader now supports the diffuse color from the mtl file
INT: moved light management to the PhondShader class
INT: managed to get multiple meshes on the screen but the DEPTH_TEST is not working
INT: extracting VBO logic in its own class
INT: started extracting the VAO in a seperate class
INT: finished extraction of vertex array from the mesh class
INT: renamed buffer in vertexbuffer, reuse size from indices IBO