The exception thrown from MediaFile will be caught and simply result in
no thumbnail at all right now. In the future we might use a catch-all
and have a "cannot generate preview"-icon or something.
VideoThumbnails requires php5-ffmpeg and php5-gd.
The parent class for our database objects, Managed_DataObject, has a
dynamically assigned class in staticGet which objects get put into,
leaving us with less code to do the same thing.
We will probably have to move away from the DB_DataObject 'staticGet'
call as it is nowadays deprecated.
Some minor database changes for file tables. Namely:
* Added a timestamp to all tables
* Added a filename column for local files
* Change some tables that had unnecessary auto-increment primary
keys when they had another unique column that should act as
the primary key
* Change engine from MyISAM to InnoDB for a couple of files.
Also, rebuilt the DB_DataObject files for all these tables.
