modify powerpoint, update script marmiton.sh, add while question in qsts_sys_ex.txt, update project explanations in Système_exploitation.txt
modify script with blanks and special characters management, modify the how_to_marmiton file and project explanation. Add question/answer in qsts_sys_ex file
Merge pull request #125 from ameliemarichal/master

add how_to_marmiton, modify powerpoint, update script marmiton.sh, add while question in qsts...