Boost.Build 2.0-m11

Boost.Build is a system for large project software construction, which is simple to use and powerfull. Boost.Build project is an onging project to rewrite Boost.Build, improving design and making it more extensible.
Main features:
- Simple and high level target description language. In most cases name of target and list of sources is enough.
- Variant builds. You can build with your choice of basic variants (e.g. debug, release, profile...), toolsets (e.g. gcc and msvc) and specific properties (e.g. inlining off) from a single command invocation.
- Portability. ``Feature Normalization allows to fine-tune targets independently from the toolset used, and modular toolset descriptions are employed to generate actual build instructions.
- Multi-project builds. Several projects can be combined and built together, with dependencies correctly tracked. Typically, the setting (like include paths and defines) needed to use other project will be handled automatically.
- Extensibility. New file types and tools can be easily added
Enhancements:
- Support was added for several new tools, including the Qt4 library.
- An "indirect requirement" feature was added.
- Several improvements were made in the "install" target.
- The --build-dir, --debug-building, and --clean-all command line options were added.
- Numerous bugs were fixed, and interface improvements were done.