Move everything to public/ dir
Make more config settings required

BREAKING CHANGE: you'll have to add the appropriate variables to your
local .env file. See the .env.example file for inspiration.
Require the twig templating system
Ignore the cache directory
Move most of the app to a Twig template system

This is a huge, BREAKING change.

The following features do not yet work (i.e. will throw exceptions):

 - First Mention tool

 - Following Comparison tool

- Signout

- Signin

Everything else has been moved over to use Twig. For now there's just
a global `render` function that's made available w/in bootstrap.php, but
obviously that'll be moved into controllers at a later point.

There are some weird implicit variable dependencies hanging around,
including expectations that `$alpha` and `$start` are both set. This
commit removes many of them, but we need to make sure to get any that
I missed.
Add a bottom margin to <p> tags
Fix broadcast lookup w/ strict variables
Fix some leftover <?php tags in twig views
Put everything shared in a Container class
Fix missing auth URL in index.twig
Refactor some of the adnlib, change callback URLs

This also adds a centralized method of accessing params via the
Container class (i.e. Container::getParam($key, $default)) so we can use
that instead of the `global` keyword (which is ugly and error prone).
Add /signin.php, /signout.php endpoints

Also sure we're using the new session endpoints in the auth_menu
partials
Add tags (phptags) target to RoboFile
Require settings.php in the bootstrap file
Move the first mention tool to Twig
Fix missing auth_url in unauth_message.twig
Add almost-working follow comparison tool

The only thing missing is the actual follow logic
Add new logs folder
Begin using Silex, break a whole bunch of things

Everything's broken again but at least it's slightly more fun to work
with.
Add an editorconfig file