Added slideshows and other improvements

- Using rss directly as datasource
- added timeouts and fallbacks
- added slideshows:
-- random: goes through all photos randomly
-- lastalbum: goes through photos of last album (using rest)
-- mini: goes through latest photos (for embedding)
- index.html will go trough slideshow but goes back to live-gallery
when there are new photos found for a limited period of time.
- using url variables for customization like simple and type of
slideshow