These site settings are very hard to explain and only applicable for very
specific Discourse setups.
If an admin "enables staged users" which is used in support scenarios then
all staff can send "messages" directly to an "email".
The setting allows you to extend this to TL4 or any trust level.
Actual use case would be a support type setup with restricted staff. It is
quite rare so hiding this for now and re-evaluate keeping the setting in
2019
* FIX: don't allow inviting more than `max_allowed_message_recipients` setting allows
* add specs for guardian
* user preferences for auto track shouldn't be applicable to PMs (it auto watches on visit)
Execlude PMs from "Automatically track topics I enter..." and "When I post in a topic, set that topic to..." user preferences
* groups take only 1 slot in PM
* just return if topic is a PM
* drafts in user profile: only show to user herself (not to admins), use avatar replying to (instead of topic OP), add keyboard shortcut for drafts, simplify display labels
* use JSON when testing Draft.stream
* add drafts.json endpoint, user profile tab with drafts stream
* improve drafts stream display in user profile
* truncate excerpts in drafts list, better handling for resume draft action
* improve draft stream SQL query, add rspec tests
* if composer is open, quietly close it when user opens another draft from drafts stream; load PM draft only when user is in /u/username/messages (instead of /u/username)
* cleanup
* linting fixes
* apply prettier styling to modified files
* add client tests for drafts, includes a fixture for drafts.json
* improvements to code following review
* refresh drafts route when user deletes a draft open in the composer while being in the drafts route; minor prettier scss fix
* added more spec tests, deleted an acceptance test for removing drafts that was too finicky, formatting and code style fixes, added appEvent for draft:destroyed
* prettier, eslint fixes
* use "username_lower" from users table, added error handling for rejected promises
* adds guardian spec for can_see_drafts, adds improvements following code review
* move DraftsController spec to its own file
* fix failing drafts qunit test, use getOwner instead of deprecated this.container
* limit test fixture for draft.json testing to new_topic request only
