[NLnet #3] Implement support for personal notes

Unstarted Issues (open and unassigned)

Ongoing Issues (open and assigned)

Completed Issues (closed)

AlekSIS-App-Alsijil · Think about tardinesses
#273
AlekSIS-App-Alsijil · Add management of tardinesses
#263 part::frontend type::feature workflow::discussing
AlekSIS-App-Alsijil · Add personal note management dialog in course book
#260 part::frontend type::feature
AlekSIS-App-Alsijil · Add dialog with each lesson's students
#259 part::frontend type::feature