MDL-40054 mod_lesson: replaced 'grade view' add_to_log call with an event
MDL-40054 mod_lesson: replaced 'update highscores' add_to_log call with an event
MDL-40054 mod_lesson: replaced 'view highscores' add_to_log call with an event
MDL-40054 mod_lesson: replaced 'start' add_to_log call with an event
MDL-40054 mod_lesson: replaced 'end' add_to_log call with an event