(310) Changed "TARGET_HOST_UNIX_X11" to "TARGET_HOST_POSIX_X11" to avoid
trademark issues, per Joe Krahn; also rationalized the other "TARGET_HOST"
definitions
+
+(311) Added futher callback functionality to the CallbackMaker demo program.
+Also added a prompt for user input to highlight a difference betwen GLUT
+and "freeglut"
+