add own timeline, optimizations

Dockerfile

lectures/templates/lectures/includes/lecture.html

lectures/templates/lectures/view_group_lectures.html

lectures/templates/lectures/view_groups.html

lectures/templates/lectures/view_lecture.html

lectures/urls.py

lectures/views.py

shared/static/shared/base.js

shared/static/shared/base.js.LICENSE.txt

shared/static/shared/shared.js

shared/static/shared/shared.js.LICENSE.txt

shared/static/shared/style.css

shared/static/shared/view_group_lectures.js

shared/templates/shared/includes/base.html

shared/templates/shared/includes/double_heading.html

static_src/view_group_lectures.js

webpack.config.js