type mismatch bug.
2. Fixed the names of of some Standard C++ header includes
to prevent g++ 3.2.1 from complaining.
3. Lots of minor fixes for all the files in the directory include/3D
to bring the library up to date with g++ 3.2.1 standards.
4. Fixed some header file names in sample/ directory.
5. Added a check for qhull_a.h header file and fixed config.h include
in Polyhedron.cpp.
6. Added a check for qhull library and now depending on its presence
the -lqhull switch is added during compilation.
