Directories can now be displayed as a 'blogdir', which treats the files
in the directory as if they were blog entries: they are sorted by
modification time, most recent first, and then they are all displayed
inline with a title.

A chunk of this behavior is controlled by templates and new renderers.
'blogdir' is a new view, only valid for directories, which uses
((blogdir.tmpl)). The ((blog::blogdir)) renderer does the direct
expansion, running each file through the template ((blog/blogentry.tmpl)).

There are also new renderers for the new blog-like time format and for
showing the owner of a file. (Currently the Unix and/or RCS owner.)

This is ... how shall we say it ... not hugely scalable over the long
run in terms of time structure and number of entries.