Doxygen documentation comment tidy up for zinc/graphic.h.  https://tracker.physiomeproject.org/show_bug.cgi?id=3535
Doxygen documentation comment tidy up for zinc/graphic.h.  https://tracker.physiomeproject.org/show_bug.cgi?id=3535

git-svn-id: b9baf8c2d14a71b3ba9c27a102eb6e792fc13348@9624 3c1deb5b-d424-0410-962d-aba41a686d42

hsorby/zinc,hsorby/zinc,OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc