Programs from Chapter 9

example1.cpp: interactive particle simulation with particles inside a box
   To bring up the menu, click the middle mouse button inside the
   window. For all the programs that use menus, the glsl files for
   the LINUX_VERSIONS directory should be the same as those in the
   MAC_VERSIONS directory. Otherwise, you would find that the menu
   items are greyed out. They are still affective but not being able
   to see the text for individual menu item does not help.

example2.cpp: fractal

Du Huynh
March 2017
