build system for configuring and building when some modules are absent (currently in place only for the Stereo module). Added a mechanism to remove certain modules in distributions. Added pixel_cast_rescale<> and fixed up channel_cast_rescale<>. Changed image views with non-virtual call operators to all use defaulted third parameters rather than separate two- and three-parameter forms. Switched to passing channels and pixels by value in inline functions. Fixed a few pixel type bugs for integer channel types. Added addition and subtraction of PixelGray and scalars. Made Algorithms.h more uniform, and added some unit tests for it and Statistics.h. Fixed a few Windows portability bugs, mosty notably timing support in Debugging.h. Changed Vector and Matrix string output formats to better match the pixel type formats. Tidied up ImageView.h a bit. Added a tools directory for high-level command-line tools, with the seeds of a (possibly ill-conceived) general image manipulation tool.