* Base class of all possible Progress.
* ProgressListener inherits this base class.
* Add documentation.
* Swig: add feature "director" to the base class.

the class implements the IProgress, to display a progress bar in
console.

* Manage cases when we need an IProgress but don't care of a progress
bar.
* Use it in avMeta app: we want the file infos, but don't care of the
progress bar.

* Create ProgressListener.cpp.
* Add include to iostream in Transcoder.

* Contains all files related to the progress.
* Also contains corresponding swig interface file.

* 3 classes / files: IProgress, ConsoleProgress, NoDisplayProgress.
* Add a cpp file just for ConsoleProgress (the implementation is more
'complicated' than the others).