includes cache of latest version and page to view if updates are
available with a link to the latest update's release notes and a link to
check for the latest update now, refreshing the cache manually.

Ref T675

This makes the naming scheme more consistent with other funcs.

Ref T565

This enables admins to customize their landing / home page via the Admin
dashboard -- including the text at the top of the page and the section
below it. It keeps the current default text, falling back to it if the
user hasn't overwritten it.

Ref T565

Closes T651

Ref T613

Now admins can choose a title for their About and Privacy pages; now
editable through the instance page editor.

This adds `title` and `content_type` fields to the `appcontent` table,
requiring a migration by running `writefreely --migrate`

The content_type field specifies that items we're currently storing in
this table are all "page"s; queries for fetching these have been updated
to filter for this type. In the future, this field will be used to
indicate when an item is a stylesheet (ref T563) or other supported
type.

Ref T566

This adds a "Pages" section to the admin part of the site, and enables
admins to edit the pre-defined About and Privacy pages there, instead of
on the dashboard itself.

It also restructures how these pages get sent around in the backend and
lays the groundwork for dynamically adding static pages. The backend
changes were made with more customization in mind, such as an
instance-wide custom stylesheet (T563).

Ref T566

This includes:

- A new `user_invites` config value that determines who can generate
  invite links
- A new page for generating invite links, with new user navigation link
- A new /invite/ path that allows anyone to sign up via unique invite
  link, even if registrations are closed
- Tracking who (of registered users) has been invited by whom

It requires an updated database with `writefreely --migrate` in order to
work.

This closes T556

This enables paging through the entire list of users.

Ref T553

This enables admins on multi-user instances to see all users registered,
and view the details of each, including:

- Username
- Join date
- Total posts
- Last post date
- All blogs
  - Public info
  - Views
  - Total posts
  - Last post date
  - Fediverse followers count

This is the foundation for future user moderation features.

Ref T553

This adds a "Reader" section of the site for admins who want to enable
it for their instance. That means visitors can go to /read and see who
has publicly shared their writing. They can also follow all public posts
via RSS by going to /read/feed/. Writers on an instance with this
`local_timeline` setting enabled can publish to the timeline by going
into their blog settings and choosing the "Public" visibility setting.

The `local_timeline` feature is disabled by default, as is the Public
setting on writer blogs. Enabling it adds a "Reader" navigation item and
enables the reader endpoints. This feature will also consume more
memory, as public posts are cached in memory for 10 minutes.

These changes include code ported over from Read.Write.as, and thus
include some experimental features like filtering public posts by tags
and authors. These features aren't well-tested or complete.

Closes T554

This allows users to load a different configuration file instead of the
default config.ini. It works in combination with other configuration
actions, like --config and --create-config.

This changes what displays in the NodeInfo, and in the future might be
used for other things.

This is almost all of T541

This allows admin to edit these pages from the web, using Markdown. It
also dynamically loads information on those pages now, and makes loading
`pages` templates a little easier to find in the code / more explicit.

It requires this new schema change:

CREATE TABLE IF NOT EXISTS `appcontent` (
  `id` varchar(36) NOT NULL,
  `content` mediumtext CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `updated` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

This closes T533

Start of T538

Usage: writefreely --reset-pass <username>

This closes #25, closes T534