use new capa_alert div for error messages, clean up debugging

Prepare lms for upcoming discussion service changes.

Fixing textbook bugs that didn't appear in 6.002x

This isn't a great fix, but I'm confused what's going on. It's something
in JQuery.TreeView. We write out the HTML correctly, but the lastExpandable
style causes the list item to not be expandable. This didn't bite us in
6.002x because the last item was an appendix that isn't expandable anyway.
It does affect 6.00x, where the last item is Chapter 5 at the moment.

fixed styles for checkboxes

polished multiple choice question styles

Fix CSV downloads when there are non-ASCII chars in student data, and pr...

Fix CSV downloads when there are non-ASCII chars in student data, and prefetch groups info to speed up the grades page

Make the default topic a dict so it doesn't error on courses that don't ...

Don't break on empty answer string

show full sidebar title; blockquote and list styles for comments

Feature/cale/cms remove wips

Disabled pipeline wrapper for compressed CSS.

Use display names for module edit links in the cms

Feature/cale/cms drag and drop children

onreset rerandomize option

Make saving also save the children in the #sortable element (TODO: name the #sortable element better)

Custom tabs