[boost] [program_options] good work

I am really excited to see program_options progress. From my limited testing so far it looks really good, and I have been looking forward to using it in my code. I hope we can add it to boost soon, because I'm reluctant to rely on unreleased boost code. The doc needs work. It was hard for me to find the doc for the function parse_environment for example. There needs to be links from the top-level html page. Also, how can I build the html docs myself from the distributed xml? It looks like I need the "boost v2" build stuff, but I don't know what that means.