== New: _/oldest/_ virtual directory restriction

DWiki has long been able to give people the latest N things in a
virtual directory context (as _latest/<N>_). Now it can give them the
oldest N things, using the obvious syntax: _oldest/<howmany>_.

Just to show off, ranges properly convert themselves into 'oldest/<N>'
at the end of their run, just as they convert themselves into
'latest/<N>' at the start.

Documentation has been updated appropriately.