#49 Photocast support

[Maurits Rijk]

iPhoto support Photocasting (http://www.apple.com/ilife/iphoto/features/photocasting.html). Maybe we can create a plug-in that support this. For example it could show the thumbnails in the rss feed which then could be opened in the GIMP. As an alternative (should become a separate feature request) we could add an option to the Picture Package plug-in to load from an Photocast feed.