Merge branch 'feature/extra-lesson' into 'master'

aleksis/apps/chronos/admin.py

aleksis/apps/chronos/migrations/0014_extra_lesson.py

aleksis/apps/chronos/models.py

...sis/apps/chronos/templates/chronos/partials/elements.html

aleksis/apps/chronos/templates/chronos/partials/event.html

...apps/chronos/templates/chronos/partials/extra_lesson.html

aleksis/apps/chronos/templates/chronos/partials/lesson.html

aleksis/apps/chronos/templates/chronos/partials/room.html

aleksis/apps/chronos/templates/chronos/partials/subject.html

...ps/chronos/templates/chronos/partials/subject_colour.html

...is/apps/chronos/templates/chronos/partials/subs/room.html

aleksis/apps/chronos/util/build.py