New parser and bug fixing

There was always an error with adding song id in database. Now, it
works properly. There is also the first view of SearchMp3 scan
function(not terminated).
Song selection improvement

Now, all parsing classes will use one fonction to display available
songs and take user choice.
Brand new DownSound version

The development was too disparate.
In this new version, the code has been completely revised and focuses
on the essentials: downloading music.
However, it is not yet functional.