Squashing and merging ...
* Each assigment should have the options to have its own set of hints #278
* Updating lessons due to changes from #278
* Enable i18n client side #312
* IDOR move hints to assignment and enable i18n #312
do not need to support anymore in 8.0:
- Introduced DI thoughout the code base
- Removed most superclasses of a lesson
- Hammerhead is now simplified to only one line of code
- Cleaned up WebSession
- Removed code which dealt with user roles, lesson fetching, username etc
- LessonTracker improvements
- Removed almost all code from the Screen class
- Removed ECS from the container project
- Removed adminstration pages, contained a lot of ECS codes which is much
simpler to just rewrite when necessary
