In file_movie.on_button_accept_clicked() file_movie.store_file() and
restore_file() are called. These methods don't exist; it looks like the
intent was to call store_element() and restore_element().
Testing confirms this; properties are now applied to all the selected
files.
Fixes Issue #79
In the old code, eval() and exec() were used to insert properties in
an object with an specific name. This is clearly an ugly solution,
when the right way is to use self.__setattr__ and self.__dict__.
This patch replaces that ugly code with new one that follows the
pythonic way of doing the things.
