Is the fastcgi_request method the best interface for Bryar::Frontend::FastCGI?
Passing the variable to $bryar->go() looks more elegant, but it would
require restructuring it and Bryar::Config to support merging new
configuration values after the object has been created.
Could this be useful in other situations as well?

The Sitemap renderer needs to be much more configurable.
Maybe we need a way to declare class-specific configuration directives
in the new and go methods of Bryar (see above for another possible use).

The TT renderer badly needs to be configurable. See above.

Instantiate more classes to simplify the interfaces. (?)

Update Bryar::_doit to support caching the collector output instead of
the renderer output, to allow using dynamic templates.

Remove all calls to chdir(2).

Add support for trackbacks.

Add many more tests.