Prepare release 2.5

See merge request !280

Resolve "Supervision Substitution entering"

Closes #185

See merge request !279

Resolve "[UI] Redesign Daily Lessons"

Closes #165

See merge request !276

Do release 2.4.2

See merge request !278

Merge branch '184-lessons-without-any-groups-are-displayed-as-cancelled-if-there-is-any-event-in-the-same-time' into 'master'

Resolve "Lessons without any groups are displayed as cancelled if there is any event in the same time period"

Closes #184

See merge request !277

Resolve "Selecting date in substitutions list yields NaN and 404"

Closes #183

See merge request !275

Fix equal lessons teachers

See merge request !274

Resolve "Use TimetableDataChangeTracker while managing substitutions"

Closes #181

See merge request !273

Drop support for GitHub

See merge request !272

Prepare release 2.4.1

See merge request !271

Fix substitution form again and add comment field

See merge request !270

Resolve "Substitution form doesn't work at all"

Closes #179

See merge request !269

Resolve "Beautify substitution form"

Closes #177

See merge request !267

Do release 2.4

See merge request !263

Translations update from Weblate

See merge request AlekSIS/official/AlekSIS-App-Chronos!255