Moving stack design/tutorial into doxygen design.dox and renaming template parameters for readability.
Moving priority queue design into doxygen design.dox, clarifying documentation at some points.
Moving documentation of STXXL sort, ksort, generate, for_each, for_each_m, find into doxygen design.dox, clarifying documentation at some points.
Customizing doxygen using CSS and a layout file.