Record changes from last year. Update Changes.txt

 - Fix strncat limit in rboxlib.c.  More to do.
 - Qt project files: Remove gcc options from DevStudio builds
 - libqhull.pro: Comment out -Wno-sign-conversion
 - qt-qhull.cpp: Move QHULL_USES_QT before the includes
 - qvoronoi.htm: Remove quotes from qvoronoi example
 - qhull-cpp.xml: Add naming conventions, try, Temporarily, p, end, private, error
 - Changes.txt: More to do.  Links to build systems