Prior to this commit, it was impossible to 'use' a route from a separate
namespace for use in a 'routes!' macro. Naturally, this was a common
source of confusion amongst users. This commit obviates this deficiency
by generating a "proxy" structure that can be imported and converted
into a 'Route'/'Catcher' or their static variants.
This change is largely backwards compatible but can break existing code
when routes are named identically to other types in the namespace.
Every code example is now fully runnable and testable. As a result, all
examples are now tested and include imports. Relevant imports are shown
by default. Code examples can be expanded to show all imports.
Fixes#432.
Sergio Benitez
Jacob Pratt
Jeb Rosen