Replace dependency on PIL with Pillow.

Description:
The package PIL appears to be unmaintained since 2009. The fork Pillow is
compatible and alive.
Add support for movies with a "sidecar"-photo that contains the metadata of the movie and, usually, a thumbnail.
Simplify MovieWithMedatada by using existing methods for renaming.
Add support for raw photos with sidecar photo for metadata.
Prefer usage of method for path updating instead of direct attribute change.
Rename modules and classes for media files with sidecar files for metadata.
Add tests for rich movies.
Remove unneeded newlines.
Make public methods required by other classes.
Fix assignment of media and metadata files and make them public.
Update file type for rich media.
Fix test for rich media.
Remove inactive code.
Make MediaRich an abstract class.
Add missing methods to rich media.
Fix rename_as and move_to_directory_with_date in rich media.
Add test data for rich raw.
Add tests for RAW rich media.