Insert new header comment block, remove old one, manually improve file comments (defines / implements), change brief function description to doxygen format, remove some outcommented code

All composite objects are now derived from ICompositeSample, which in turn is a tree of ISample objects.

On the way to add roughnesses of layers: new classes IRoughness, LayerInterface, lots of comments and const references. New Doc/Doxyfile for oxygen generation.