Metrics tab shows student data:
  -Count of students opened a subsection
  -Grade distribution per problem

for each section/subsection of the course.

Implemented for both the old and beta dashboard
Controlled by a feature flag 'CLASS_DASHBOARD'
Data is aggregated across all students
Aggregate data computed from courseware_studentmodule

Students no longer see a tooltip nor any button affordance (i.e. cursor
and color change on hover/focus) on the pinning feature. For moderators,
the tooltip is now correct when a thread is pinned, the button is
accessible for keyboard-only users and screen readers, and an error
dialog now appears if an error occurs in attempting to pin/unpin.

JIRA: FOR-192

UX-351

Removed inappropriate section tags. Because screen readers announce each section, they should not be used unless they are actually defining meaningful sections.

LMS-2156

If neither start nor advertised_start has been changed from default
don't show the course start date.

This allows us to accept course registrations for courses whose start
date is yet TBD.

Users will first be shown the first 25 responses of a viewed thread and
then have the option of loading 100 more at a time until all responses
have been loaded. This mitigates the performance impact of very large
threads by avoiding the need to render and transfer over the network
all content of a large thread at once. It will also allow students with
slower browsers to interact with large threads even if they cannot load
all of the responses.

- Clarify checkbox description wording
- Wrap checkbox and envelope icon in div to make it stand out
- Added styling for wrapper div
- Wrap label element around div to allow clicking the envelope to activate the checkbox
- Indented HTML and fixed if wrapping issue

- Added note to instructors on Forum Admin page of Instructor Dashboard.
- Made Role Info divs permanently displayed, but under the user list.

LMS-2121

JIRA: FOR-373

This includes removing the "PREVIEW" label for the preview pane from CSS
and adding it to the generated DOM.

* adds in Sass placeholder to mirror older/inherited button styling used in LMS
* uses light theming Sass variables for button styling
* adds specific selector for certificate download button

LMS-1584

* provides new .scss file for developers to add temporary/in-progress Sass for further refactor/polish
* cleans up note/import order in all application scss files

* uses Google Web Fonts reference rather than local files
* removes unused local font files
* adds in semi-bold weight support

This button has been broken for at least a year, so the code has
suffered from bit rot and should be reimplmemented if the feature is
necessary in the short term (which is unlikely since it has been broken
for so long).