filepath was used inconsistently throughout the hugolib. With the
introduction of source and target modules, all path are normalized to
"/". This simplifies the processing of paths. It does mean that
contributors need to be aware of using path/filepath in any module other
than source or target is not recommended. The current exception is
hugolib/config.go
Introducing the target module in hugo. This provides the simple
interface for writing content given a label (filename) and a io.Reader
containing the content to be written.
If site.Target is not set, it defaults back to the original behavior of
writing to file system.
In hugolib/site_url_test.go I have an InMemoryTarget for testing
purposes and use it to see if the final output of a render matches.
