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 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

- New editor nav
- New backend nav
- Support for drafts
- Different footers on backend

This is mostly unnecessary, and ensures users don't get confused when
their site doesn't show up because the server isn't seeing a
correctly-set Host header.

- Database schema changes, removing obsolete custom domain-related code
- Missing user structs
- Setup verbiage changes
- Missing routes
- Missing error messages

This includes the '/' route handler

Includes new instance stats and the new option to show user stats, as
well.

This includes config changes, collections, posts, some post rendering
funcs, and actual database connection when the server starts up.

Includes app config and some initialization