STUD-1726

Previously on the send email page of the instructor dashboard, instructors could only view
task information about emails they've sent for their course in the past.
In addition to this, I've now added the ability to see the content of all previously sent emails.

A "Sent Email History" button has been added to the page. When clicked, a table displaying the
subject line, number of emails sent, and date/time of submission for each previously sent email
is created. An instructor can then click on any subject line to see the content of that email,
displayed in a modal window that appears on the page.

The window is also equipped with a "copy email to editor" button, which copies the emails contents
to the tinyMCE editor, so that an instructor can easily resend an email that they've sent
in the past.

 Added a new advanced setting; invitation_only

 If invitation_only display "Enrollment in this course is by invitation only"
 Otherwise, if outside of enrollment period display "Enrollment is Closed"

 This issue is logged at LMS-2670

 Also fixed in this PR is issue LMS-2717; even though the Register button was greyed out,
 clicking it sent one to the registration page.

STUD-302, STUD-303

STUD-1658

STUD-1312

refactor _generate_items_for_subtask not to chunk queries

use django's iterator methor for querysets

remove bulk email query settings

use read_replica if available, since this is read-only

update changelog

Changes requested in PR

This commit implements STUD-1490, allowing creation of components
on the container page. It also enables the delete and duplicate
buttons now that new content can be created that would benefit.

Note that it also creates shared functionality for adding components,
and refactors the unit page to use it too.

Added new error message that displays when HTML5 video is not supported altogether. Make sure spinner gets hidden when error message is shown. [BLD-638]

LMS-1296

STUD-1562

Set initial video quality to large instead of default to avoid automatic switch to HD when iframe resizes. [BLD 981]

STUD-1562

Features by Jeff Ericson and Nick Parlante squashed
down to one commit.

-shuffle of choices within a choicegroup (Nick)
-answer-pool subsetting within a choicegroup (Jeff)
-masking of choice names within a choicegroup, (Nick)
 used by shuffle and answer-pool
-targeted-feedback within a multiplechoiceresponse (Jeff)
-delay-between-submissions capa feature (Jeff)

player.getAvailableQualityLevels returns a non-empty array, it will eventually display, if HD qualities are available (highres, hd1080, hd720). [BLD-937]

STUD-1306

LTI: Update resource_link_id to change on import to another system or context (BLD-768).

Changed tiny-MCE to not load CSS files dynamically.
Added CSS files for tiny-MCE in env files.
Moved TinyMCE files to directory structure required by Jake command.
Changed clients of "tinymce.min.js" to use "tinymce.full.min.js" instead.
Updated CHANGELOG to indicate tinymce version 4.0.20.
Renamed tinymce.css.
Directions for creating tinymce.full.min.js and commenting of edX changes.
Updated comments related to disabling dynamic JS and CSS file loading in tinymce.
Allow TinyMCE to handle CSS within the iframe.

Detailed commit messages:
deleted old tinymce

new tinymce
js changes to support new tinymce
scss changes for alignments

Include all the controls on the toolbar that we previously had.

Changes to support Bulk e-mail usage.

adding new studio skin for TinyMCE4

Get handling of static image links working again.

Delete old Studio skin.

Version 1.3 of CodeMirror plugin.

Modify paths for location of CodeMirror files.

Fire events when CodeMirror Editor is open and closed.

Needed to switch static links back and forth.

Remove CodeMirror tabbed editor.

fixed tinymce visual editor css

Change how we detect that an image has been inserted.

made the codemirror look more studio-like

reordered the tinymce buttons

Update unit tests.

Update acceptance test for image plugin.

Make sure to strip out temporary caret.

It can get left behind in style blocks.

Test for style block being maintained.

Allow TinyMCE to create p's, else formatting doesn't work.

Add tests for toolbar buttons and converting links.

Add test for code format toolbar button.

Remove unnecessary code.

Remove unused testing templates and unused tabs.

Update tinymce paths.

Fire an event with the link plugin closes so we can rewrite links.

pep8

Updates from code review.

Change the name of the button to "Edit HTML".

Changed menu name for consistency, but we don't show it.

Changed name of "code" toolbar button to "Code block".

Switch from tabbed Visual/HTML Editor for HTML modules to showing the code editor as a plugin within TinyMCE (triggered from toolbar). STUD-1422

Fire events before and after the image dialog is shown.

We use this to rewrite links.

Change the event handling for image plugin.

Fixes FireFox bug, and allows us to correct the image path when we show the plugin (as opposed ot only correcting path when we close the plugin).

Code review feedback.

Fire events before and after the link dialog is shown.

This allows us to convert the static links.

Remove unnecessary helper method.

keeping the component editor inside the component window

Use compressed CodeMirror file.

replaced code icon in TinyMCE editor; simplified UI on TMCE toolbar

Change code editor icon to say HTML.

Move code style block button.

Update tests for minor UI changes.

Code editor button no longer shows an icon, and code style toolbar button location has moved.

Fix typos.