This finally adopts the new standardized interfaces instead of the
work-in-progress ones with the `Interop\` prefix.
Since we have now updated to PHP 7.1, we can also use Stratigility
3.0 as the middleware dispatcher.
This prevents garbage collection to randomly break the installer:
before installation, the models that are being accessed have no
database connection.
Now, the middleware is only mounted into the forum's middleware
stack. I want API requests to have stable performance, and the
forum middleware stack is only mounted when Flarum is installed.
This class holds all information relevant to a local Flarum site,
such as paths and local configuration. From this information, it
is able to instantiate a Flarum\Foundation\Application instance,
which represents a Flarum installation's runtime.
This will also be useful for setting up e.g. multi-tenant
environments.
The various middleware can be registered in the service provider,
and the rest of the logic can all go through one single front
controller (index.php in flarum/flarum, and Flarum\Http\Server in
flarum/core).
This will also simplify the necessary server setup, as only one
rewrite rule remains.
