This changes all variables and functions from using Suspend{ed} to using
Silence{d} as well as documentation, errors and logging.

This fixes a template rendering issue caused by bad references to $.Host
in pinned posts links on single-user instances.

Closes #207

the change to take a hostname in Post.CanonicalURL broke a few template
using that function. This adds a Hostname string to the Post being
passed to templates and passes it to calls to Post.CanonicalURL

- update error messages to be correct
- move suspended message into template and include for other pages
- check suspended status on all relevant pages and show message if
logged in user is suspended.
- fix possible nil pointer error
- remove changes to db schema files
- add version comment to migration
- add UserStatus type with UserActive and UserSuspended
- change database table to use status column instead of suspended
- update toggle suspended handler to be toggle status in prep for
possible future inclusion of further user statuses

Previously, the new pinned post link would appear in the site header,
instead of the blog header.

This adds a new config value: `chorus` that signifies an instance is
more about the Reader view than individual blogs / writers. When
enabled, user navigation will show on all pages, including About,
Reader, and Privacy (ref T680).

It also uses different collection templates that keep the instance-wide
navigation at the top of the page, instead of the author's name --
again, branded more for the collective than the individual.

Ref T681

This shows About, Reader, Log out links on backend user pages when
logged in. It also adds "New post" buttons on the backend pages and
blogs.

Might as well do this right away, we're here anyway.

It now loads unconditionally and highlights all code blocks.

TODO: optimize to not load when there are no blocks

This is a first stab at having a configurable code highlighting option,
similar to the MathJax rendering option. This change makes a checkbox
in the settings for code highlighting using the highlightjs.org
library.
What works: code highlighting in multi-user env is like I would
expect. single and anon(?) needs work

Things to resolve/consider:
- does the .IsCode test for code highlighting need to stay? At least
this and that should use the same version of the highlight.js lib.
- can the common templating part be 'included' somehow?
- the anon vs single-user vs multi-user code is not completely
clear (to me)
- bring js to local instead of cloudfare cdn (perhaps combine with
MathJax)

This closes #15

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