Experimented with the new impl specialization features of Rust. They work! But
they're not quite there yet. Specifically, I was able to specialize on
`Responder`, but when trying to remove the macro in `FromParam`, it didn't work.
See https://github.com/rust-lang/rust/issues/31844.
At the moment, I simply install the first route I see into the Rocket struct
directly. This is quite terrible. What's worse is that I assume that the Route's
path and handler are static! The handler, actually, does have to be static, but
its response may have whatever (valid) lifetime, though I'm not sure anything
but `static makes sense. I'll think about it.
In any case, the weird `static` restrictions need to be removed, and I need to
think about which lifetimes are safe here. IE: Must all routes be static? Can I
use a closure as a route? (that'd be neat). If so, how do we make that work?
In any case, it's nice to see SOMETHING work. Yay!
Subset of list of changes:
* Split up decorator and macro into their own files.
* Fully parsing the path parameter and verifying against the function's args.
* Actually calling methods to fetch and convert the request parameters.
* Actually calling methods to convert the handler's return type.
* Sketched out more of the Request/Response structures.
Pretty close to having a fully working MVP.
Here's what works so far:
* The `route` decorator checks its inputs correctly. There's a nice utility
for doing this, and it's working quite well at the moment.
* The `route` decorator emits a `route_fn` and a `route_struct`. The `routes`
* macro prepends the path terminator with the route struct prefix. The
* `Rocket` library can read mount information (though not act on it properly
just yet) and launch a server using Hyper.
