into the core helper. Clean up interactions so that when we remove an
album cover we pick a new one, or clean out the old album cover if
there are no other choices.
1) Fixes Ticket #208
2) Fixes Ticket #190
3) Fixes an unticketed issue where two items could collide when
creating the thumbnail and/or resize. For example, loading a.flv and
a.jpg would have generated the same thumbnail image. This change adds
a random value to the name to avoid conflicts.
4) Added item::__set() to clear the relative path if the name changes
1) move the rand_key column into core
2) don't do a max rand, just try to a get a random number less than
the current random number if that doesn't successd look the other way
key and path. This way it won't try to generate a resize for movies.
2) Changed the options on the ffmpeg command in movie::extract_image
so we actually see a frame not the black one that starts the movie.
