Rust's linting API is incredibly unstable, resulting in unnecessary
breakage to `rocket_codegen`. Rocket's lints are also not as
conservative as would be desired, resulting in spurious warnings. For
these reasons, this commit removes linting from `rocket_codegen`.
These lints will likely be reintroduced as part of a 'rocket_lints'
crate. Factoring the lints out to a separate crate means that lint
breakage can be dealt with by uncommenting the dependency instead of
waiting for a new release or backtracking nightlies. In the same vein,
it will likely improve stability of the 'rocket_codegen' crate.
This commit includes two major changes to core:
1. Configuration state is no longer global. The `config::active()`
function has been removed. The active configuration can be
retrieved via the `config` method on a `Rocket` instance.
2. The `Responder` trait has changed. `Responder::respond(self)` has
been removed in favor of `Responder::respond_to(self, &Request)`.
This allows responders to dynamically adjust their response based
on the incoming request.
Additionally, it includes the following changes to core and codegen:
* The `Request::guard` method was added to allow for simple
retrivial of request guards.
* The `Request::limits` method was added to retrieve configured
limits.
* The `File` `Responder` implementation now uses a fixed size body
instead of a chunked body.
* The `Outcome::of<R: Responder>(R)` method was removed while
`Outcome::from<R: Responder(&Request, R)` was added.
* The unmounted and unmanaged limits are more cautious: they will only
emit warnings when the `Rocket` receiver is known.
This commit includes one major change to contrib:
1. To use contrib's templating, the fairing returned by
`Template::fairing()` must be attached to the running Rocket
instance.
Additionally, the `Display` implementation of `Template` was removed. To
directly render a template to a `String`, the new `Template::show`
method can be used.
Modifying the `Rocket` structure just before launch doesn't make sense for
several reasons: 1) those affects can't influence the launch, and 2) they won't
be observed in tests. Thus, an `Attach` fairing kind was added that ameliorates
these issues.