Review configuration settings

[ywarnier]

Since the (hardcore) development of 2.0, a number of settings are probably not working as they should anymore. Most of them have already been fixed through other issues, so this is a list of some settings that have appeared during other tests and that I believe are not yet implemented as they should in the new interfaces/processes.

• course.display_coursecode_in_courselist is supposed to show the code of the course in the list of courses. It doesn't. course.display_teacher_in_courselist is fine
• course.show_navigation_menu does not seem to work but in 1.11 it used to be relatively redundant against course.show_toolshortcuts. Remove course.show_navigation_menu, we don't need it.
• course.breadcrumbs_course_homepage offers 4 options, but they are not taken into account. Normally, they should replace the "title" part of the course in the breadcrumb. Although this option might be useful in some contexts, it is really not a big deal overall and some parts (like showing the session title) could conflict with the new display. Remove it.
• course.allow_course_theme is a bit weird in the way it works (doesn't show all themes by name, then the main screen changes but not the menu unless you refresh, etc). I understand this is bound to the way the content screen for the course is just a div. Leave it that way for now, but we might want to revisit in the future
• course.course_validation: when this option is enabled, normally the teacher cannot create a course (either the creation icon does not appear or changes, or the form is updated to become a "request a course" form). This does not seem to work, so I suppose course.course_validation_terms_and_conditions does not work either
• course.course_images_in_courses_list does not seem to work. Setting it to "no" still shows the custom course thumbnails in the courses list (it should then use the default image). The title "Courses custom icons" should be renamed "Custom thumbnails for courses"
• course.course_creation_splash_screen was a way to show an introduction page just after the course creation form and before getting on the course homepage (for teachers only) to explain to them how to use the course homepage. I believe this was done for @baelmyhu 's institution, but I don't think it added much value outside of that (I don't think anyone knew about that option). Remove for now.
• course.view_grid_courses does not seem to apply anymore. I would remove it.
• course.hide_course_sidebar can be removed. It was there to hide the "Courses" block in the left menu in 1.11. It doesn't make sense in 2.x
• course.enable_unsubscribe_button_on_my_course_page does not work. It should be possible for a student to unsubscribe from a course through a simple icon if this option is enabled.
• course.course_creation_donate_link should be removed

This does not cover each option in this settings category. Other issues like this will probably follow, but it makes for a good progressive work on this larger issue of deprecated settings.