* Make the library modular usable.
* Switch to library requirements instead of source. As source puts extra source in install targets.
* Add requires-b2 check to top-level build file.
* Update dependencies.
* Bump B2 require to 5.2
* Update copyright dates.
* Move inter-lib dependencies to a project variable and into the build targets.
* Adjust doc build to avoid boost-root references.
* Update build deps.
* Change math dep real target math/tr1.
* Move include to target.
