* Private forums: CanBeSeenBy moderators, approved followers, its owner and
admin users.
* Note: the endpoint to subscribe to the forum won't allow users to follow
the private forum, so approved followers can not be created at this time,
except by adding them as moderators.
* Admins: when creating a forum they can choose "no category" to create it as
an unofficial community forum.
* Code cleanup
* More feature flag checking
* The "Newest" tab of the forum is updated with new filter options.
* Which forums: All, Official, Community, My List
* Show: By threads, All posts
* The option for "Which forums" is saved in the user's preferences and set as
their default on future visits, similar to the Site Gallery "Whose photos"
option.
* So users can subscribe to their favorite forums and always get their latest
posts easily while filtering out the rest.
* Forum Moderators
* Add the ability to add and remove moderators for your forum.
* Users are notified when they are added as a moderator.
* Moderators can opt themselves out by unfollowing the forum.
* ForumMembership: add unique constraint on user_id,forum_id.
Adds initial code for basically functional forums:
* Forums landing page shows hard-coded list of Categories along with any
forums in the DB that use those categories.
* Admin: Create, Edit forums and view forums you own or have admin rights
to modify.
* Landing page forums list shows the title/description and dynamic count of
number of Topics and total number of Posts in each forum. TODO: distinct
count of Users who posted in each forum.
* Board Index page shows list of Threads (posts) with a Replies count and
Views count on each thread.
* Thread view is basically an array of Comments. Users can post, edit and
delete (their own) comments. Deleting the first comment removes the
entire Thread - the thread points to a first Comment to provide its body.
* Reply and Quote-Reply options working.
