Pour les exercise_report
Fixing PHP notices.
Minor - fixing PHP notice.
Add installation guide section for Sendfile header - refs BT#6853
Merge remote-tracking branch 'origin/1.9.x' into 1.9.x
Merge remote branch 'upstream/1.9.x' into exercise_report
Removing only course relation in active url -refs #6977
Indentation
Using api_is_multiple_url_enabled() -refs #6977
Minor - fixing PHP notice.
Fixing query see BT#7560
Minor - removing whitespaces.
Merge branch '1.9.x' of ssh://github.com/chamilo/chamilo-lms into chamilo19
Minor - fixing PHP notices.
Fixing tools with any help see BT#6904
Minor - format code.
Minor - Format code.
Fixing condition "$lp_view_id = intval(strval($lp_view_id))". see BT#6986
Minor - cleaning code, adding error_logs.
Fixing session cleaning see BT#7407