DownSound 1.3.4(Beta) release

This new release brings a lot of improvements :
- a new code documentation
- a new log writing function
- a different user input parsing
- a new print_help function (help manual)
- a new quit function
- a finished download function
- and some bugs fixing (remove bad paths, unneeded variables, weak
references)
And also some new objectives.
Program behavior improvement

Remove all « sys.exit » line. Now all quit request will pass through
the quit function.
Bug fixing : bad infos parsing

User input was wrongly parse and it was producing a bad url. It has
been fixed by improving regex scan.
Site parsing classes development

This is the first view of different classes to parse html code by site.
DownSound 2.0(Stable)

This release brings a big change in DownSound.
Now, all research will be made by site. New website classes has been
implemented to parse html code differently for each website.
Only Mp3Skull class has been implemented for the moment.
Code documentation review
Setting usage of xml function and file

Now, there is a function to print sites name and select on which one
song will be download.
Add .gitignore
Brand new database shell

The little shell has been entirely revisited and improved.
With this new version you interact with database likely you were using
a true sqlite shell without too efforts.
Changes with shell upgrade
Merge branch 'shell'