3cd3c60b59
This PR changes the default behaviour of the discussions experience by making the previous "unit-level visibility" the default mechanism for configuring discussions. Prior to this PR, under the new discussions configuration experience, all units would automatically get assigned a discussion topic and have discussions enabled for them (other than units in graded or exam subsections). However, if authors wanted they could enabled a custom visibility mode which would allow toggling discussions on or off on a per-unit level. This PR makes this custom visibility mode the standard behaviour (and eventually, only behaviour) and enables discussion for all units by default. This replicates the behaviour that already existed, however, now gives authors control over disabling discussions for individual units by default. It also removes the ability to disable discussions for all units (while still keeping course-wide discussions) enabled.
Open edX -------- This is the root package for Open edX. The intent is that all importable code from Open edX will eventually live here, including the code in the lms, cms, and common directories. If you're adding a new Django app, place it in core/djangoapps. If you're adding utilities that require Django, place them in core/djangolib. If you're adding code that defines no Django models or views of its own but is widely useful, put it in core/lib. Note: All new code should be created in this package, and the legacy code will be moved here gradually. For now the code is not structured like this, and hence legacy code will continue to live in a number of different packages.