* Creation of a media to extract video sequences into gif files
* We add a gif method to the class Video to be able to use the Gif Media.
* Parameters where missing in the declaration of the gif function
* One parameter was badly defined in the gif method
* We use the proper media in the method gif
* We add a missing declaration in the Video class
* Update of the README file
* Modification of the README file
* We remove an empty class
