Improve CGAL basic viewer

I'm currently a Ph.D. student at the University of Southern California and focused on computer graphics. This doc proposed my detailed solutions to improve CGAL basic viewer based on my own development experience in Qt-based OpenGL design including how to achieve "clipping plane", "transparent faces", "Arrangement 2 supports", and "other basic viewers". For each goal, I studied CGAL code base, proposed my solution in steps and illustrated the goal that I want to achieve with images. Moreover, I listed the Qt-OpenGL projects and related course projects that I worked on, which will definitely help me with the implementation.

Keywords: Qt5, OpenGL, shaders, signal, slot, clipping plane, transparent faces, traits, simple basic viewers;