Moved do_load_bg_modelview() and do_insert_background() to boxfish_vrml_bg.cpp
Created todo list for the project using ToDoList from CodeProject.
http://abstractspoon.pbworks.com/w/page/1262208/FrontPage
Make background to be unaffected from polygon and shading mode.
Remove check for maximized bounding volume in scene bounds calculation.

This check is not required since maximized property does now have a different meaning.
Refactored sky_extrusion_generator into more generic class capable to create
both sky and ground (sub)spheres.