category external feed

Display feed for category in page, use simplepie and import feed
from external site and display it in category page.

This add new fields to category: the url of feed and the title
that will appear in the widget.

It uses simplepie class that came with wordpress distribution.

Upgrade

I am experiencing some problem, deactivate and reactivate the module
should fix those. Be carefull, just make a backup of table data
(prefix_category_ext_feed), deactivate plugin, then reactivate.
Thus if data about feed is not available anymore, just replace
the table.