Add support for named routes

Add a name parameter to routing annotations such as `@Get` etc.
This would allow us generate absolute or relative URLs by name and change URLs with less impact on other parts of an application. In addition this could also be used to pre-validate path parameters and create even safer applications.

## Examples
```java
@PathPrefix("/api/users")
public class UserController {
@Get("/{String:name}", name="greetUser")
public String greet(@Path("name") String name) {
return "Hello " + name;
}
}

// In other parts of the application
server.makeRoute("greetUser", "JanHolger"); -> /api/users/JanHolger
```

Start by tracing how routing annotations such as @Get and @PathPrefix are processed, then inspect the server.makeRoute entry point shown in the example. Define how route names, URL generation, and path-parameter validation should work, and verify the named greetUser example produces /api/users/JanHolger.

Written by the indexing model from the issue text.