Get and set user data

[ryanb]

User data is various information attached to a movie (such as the copyright) and can even be custom data. One should be able to get and set this information. through a simple user interface.

The data is keyed by a 4 letter code, but we could use symbols to represent common codes.

movie.get_user_data(:copyright) # get copyright details
movie.set_user_data("abcd", "foo") # set custom user data

An alternative interface is a hash, which is more ideal but might be a bit harder to implement.

movie.user_data[:copyright] # get copyright details
movie.user_data["abcd"] = "foo" # set custom user data

See page 38 of QuickTime Toolkit for more info on user data.