GitLab

Adds a method to the Corpus class which allows to arrange all diagrams
for a specific contrast and representation of all movies  together in
one tableau of diagrams.

Add documentation for the basedir attribute.

Add a file crawler for *.png files in the `_report` method of the Corpus
class which adds the availalbe diagrams for specific contrasts.

Add a corpus class which holds information about available movie files,
frames, data and visualizations in a corpus of movie files, following
the cittena movie corpus scheme.
Add a method to report the status of the movie corpus.