[boost] [tools/regression] Directory reorganization

There's some reorganization in progress in the trunk/tools/regression directory. This shouldn't affect most developers or users, since any of our Boost scripts that depend on these directory locations are being updated too. But if you've got any of your own scripts, make files, or IDE projects that depend on these directory locations, you will need to update them accordingly. Thanks to Rene Rivera for cleaning up this aspect of our tools directory structure! --Beman