Commands
node magister.mjs students # list students (works for parent and child credentials)
node magister.mjs schedule <id> <from> <to> # schedule, YYYY-MM-DD dates
node magister.mjs grades <aanmelding_id> [top] # grades (default top=50)
node magister.mjs infractions <id> <from> <to> # absences
Flow
Run students first to get each student's id and aanmelding_id. Use id for schedule and infractions, aanmelding_id for grades.