[OGDev] Refactoring CGI::Wiki::Plugin::RSS::ModWiki and OpenGuides::Feed

[Nick Burch]

Hi All

An update on my (and Dom's progress):

> * wiki.cgi notices you want the recent changes

wiki.cgi now decides if you want rss or atom, and passes that in (as 
feed_type). It now sets a feed_listing of "recent_changes", and passes 
that in too.

> * display_feed in OpenGuides.pm largely delegates to OpenGuides::Feed

This ensures it's given a feed type, and a feed listing, before passing on 
to OpenGuides::Feed

> * OpenGuides::Feed sets up the cgi::wiki instance, and calls
>   CGI::Wiki::Plugin::RSS::ModWiki

This now checks that it is given a valid feed type and listing. Since it 
only supports recent changes, it will then call the recent changes method 
on the appropriate Wiki::Toolkit::Feed (be that RSS or Atom)

(It has the infrastructure for calling other feed methods on the 
appropriate feed object, for the future)

> * CGI::Wiki::Plugin::RSS::ModWiki fetches the recent changes, and RSS
>   formats it

This has now been replaced with Wiki::Toolkit::Feed::RSS and 
Wiki::Toolkit::Feed::Atom.

These make use of Wiki::Toolkit::Feed::Listing, which handles fetching the 
recently changed nodes in a common way (and the newest appropriate node, 
for the feed timestamps).

Having used Wiki::Toolkit::Feed::Listing, they then provide a standard 
method for producing a feed of a list of nodes (generate_node_list_feed).


In future, new kinds of lists of nodes can be added to ::Listing, and the 
feeds can be configured to fetch with these. Also, other code can get 
their own list of nodes (eg via a search), and just use the appropriate 
feed module to format these into a feed (via a call to 
generate_node_list_feed).

Nick