ENH: Moved caching of C*_FLAGS* settings down to CMakeSystemSpecificInformation.cmake.  The platform files can set the defaults on the first run, and then the settings are cached at the end.

ENH: Enhanced FindITK supporting use of ITK from an install tree or a build tree.  Only one cache entry is brought into user's project, called "ITK_DIR".  This is the location of an ITKConfig.cmake file from which other settings are loaded.

In certain cases, try to guess the source directory, so that you can run cmake or ccmake without specifying source dir

ENH: Added generation of --gccxml-compiler argument to GCC-XML for msvc6, msvc7, and nmake makefiles generators.