RSS implementation

This RSS implementation use a database (in a flat file).
* It generates a list of pictures, and store it
* at the next generation, a diff is made, all new files are added at the rss feed.

To do :
* RSS feeds for folders (probablyy add a regexp, if a folder is set on the url, recover just files fith folder's name on their adress).
* Add a cache system : a little file with date of the last rss generation, and a user variable for the delay between two generations.