Here, the order is relevant, because at this
point, the application has already been booted.
Hence, all boot() methods are called immediately,
which might depend on other service providers'
register() methods having run.
In this case, the DiscussionServiceProvider
depends on the Gate class being registered in the
container by the UserServiceProvider.
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.
They will probably be refactored away at a later stage (when we get
rid of the command bus). Until then, this lets us remove the
Flarum\Core namespace and actually feels quite clean.
* Introduce user display names
It is not uncommon for forums to be intergrated with sites where users
don't have a unique "handle" - they might just have their first name,
or a full name, which is not guaranteed to be unique.
This commit introduces the concept of "display names" for users. By
default display names are the same as usernames, but extensions may
override this and set them to something different. The important thing
is that all code should use `display_name` whenever intending to output
a human-readable name - `username` is reserved for cases where you want
to output a unique identifier (which may or may not be human-friendly).
The new "GetDisplayName" API is probably sub-optimal, but I didn't worry
too much because we can come up with something better in `next-back`.
ref #557
* Apply fixes from StyleCI
[ci skip] [skip ci]
