fixe matrixes declaration

apps/display_levels/display_levels.cpp

apps/display_levels/gperf/display_levels.prof

apps/display_levels/gperf/pprof6212.0.svg

apps/display_levels/gprof/gmon.out

apps/display_levels/gprof/gprof.output

apps/display_levels/valgrind/callgrind.out.6955

apps/display_levels/valgrind/valgrind_6955.jpg

apps/display_levels/valgrind/valgrind_GUI_6955.png

sandbox_conf.yaml