Reviewed all copy constructors and copy assignments. Updated comments.

   Defined Qhull copy constructor and copy assignment [G. Rivet-Sabourin]
   Disabled UsingQhullLib default constructor, copy construct, and copy assign

- Add #error to Qhull.h if qh_QHpointer is not defined
- Define MSG_QHULL_ERROR in user.h
- Move MSG_FIXUP to 11000 and updated FIXUP QH11...