Polygons:  Enhance interface, add cube

Remove static member fonction that create polygons and make them outside
friendly function.
VBO:  Remove cube generation

vbo.cpp is currently used for loading objects to OpenGL, mainly useful after
loading a mesh object than returns three vectors for textures, normals, and
vertices
Scene:  add polygon container

the update_and_draw fonctinos updates the scenery and then draws each object.
Camera:  New class that acts as a first person camera