[boost] [Property Tree] Maintenance Takeover

Hi, I'd like to officially announce that I have, with Marcin Kalicinski's permission, taken over maintenance of the Property Tree library. Over the next week I'll take a good look at it and see what there is to be done for inclusion in an official release. At the moment, it seems like the main problem is insufficient and outdated documentation. Marcin also had other concerns regarding the library (performance and interface), and I'll see if they should be addressed before an official release as well. (Interface concerns are more pressing, obviously.) If anybody has additional comments on the library, change requests, performance data, or simple discussion of ideas, now is the time to let me now. Sebastian