This commits also implement the query reform from #608. It also consists
of many, many breaking changes. Among them are:
* Query parts in route paths use new query reform syntax.
* Routing for queries is now lenient.
- Default ranking has changed to reflect query reform.
* Format routing matching has been fixed.
- Routes with formats matching "accept" will always collide.
- Routes with formats matching "content-type" require requests to
have an equivalent content-type header to match.
- Requests with imprecise content-types are treated as not having a
content-type.
* Generated routes and catchers respect visibility modifiers.
* Raw getter methods from request were renamed and retooled.
- In particular, the index parameter is based on segments in the
route path, not dynamic parameters.
* The method-based attributes no longer accept a keyed 'path'.
* The 'rocket_codegen' crate is gone and will no longer be public.
* The 'FormItems' iterator emits values of type 'FormItem'.
- The internal form items' string can no longer be retrieved.
* In general, routes are more strictly validated.
* Logging from codegen now funnels through logging infrastructure.
* Routing has been optimized by caching routing metadata.
Resolves#93.
Resolves#608.
Resolves#693.
Resolves#476.
Here's the idea: under the `Rocket` namespace should live things critical to
writing simple Rocket apps: Request, Response, Error, etc. Nothing should be
nested more than one level deep. Only items required for more complex things
(implementing uncommon traits, etc.) should be nested one level deep.
This commit is the first attempt at realizing this.