Fleshed out GLUT callbacks and added output routines.
Added special keys callback and object centering.
Added Extras.cc to build system.
Added a method to set the center of an object.
Added cube and sphere primitives.
Added downcast tests for cube and sphere prims
Added declarations for cube and sphere primitives.
Added message prototype
Added center coordinate to render objects
Added cube object reference to Scene.cc
Added Eclipse droppings to ignore list.