Moved Qt project files into src

 -   Use shadow build directory instead of tmp (QtCreator's default)
 -   Moved targets to bin and lib
 -   Build static libraries for ease of distribution
 -   Remove VPATH
 -   Remove gcc options from DevStudio builds
 -   Remove QhullError.cpp and QhullEvent.cpp (empty files)
 -   Do not remove app_bundle from CONFIG
 -   Make -fno-strict-aliasing conditional on gcc version
 -   Added src/qhull-app-cpp.pri and src/qhull-app-c.pri for common settings
 -   libqhull.pro: Comment out -Wno-sign-conversion
 -   gcc warnings need fixing.  Does not build with gcc 4.4 and warn_on
 -   Moved projects/debian to src/debian.  Needs reorganizing

Code changes
 - Renamed RoadError::defined() to RoadError::isDefined()
 - Renamed RoadEvent::defined() to RoadEvent::isDefined()
 - Use fabs() instead of abs() to avoid accidental conversions to int
 - qconvex.c,etc.: Define prototype for _isatty
 - Rename parameters to avoid overriding other methods
 - qt-qhull.cpp: Move QHULL_USES_QT before the includes
 - qhulltest.cpp: Add closing prompt.