[boost] RTL and example are updated in the file vault

Hi all, I spent some time optimizing the RTL example discussed some time ago, as well as related parts of the library. The result (according to my estimate) is almost 10 times increase in performance. Jose, if you could time it again on your PC, we would have more accurate result. Among other optimizations, I also switched to a faster but less accurate formula for distance calculations, which lead to a slight change in the result -- apparently two stations are located at the distance of almost exactly 5 km. The library and example are at their usual place in the file vault, http://tinyurl.com/8lbmg. As always, comments are welcome. Regards, Arkadiy