Fixing wrong copy/paste
No need to add "require_once" composer already "knows" that class
Removing "class_exists"
Adding new structure for Exercises: adding "iid" fields in quiz_ tables. Adding autolaunch for exercise
Fixing DB install command due the recent changes in the data folder
Adding function comments
Replacing $_configuration['root_sys'] with api_get_path(SYS_PATH) see #6104
Fixing diffirent bugs due recent merge with the global and multiple categories in exercises see BT#5638
Renaming table name c_quiz_question_rel_category to c_quiz_rel_category see BT#5638