Cleaning code.
Set default value for 'list' type to an empty list.
Creating an iterable Namespace that is accessible in the same way that a dictionnary.
Update the license.
Change behaviour of 'parse' method.
Correct an error message.
Change behaviour of the execution of an external module. It is no longer a
python path of a module in 'sys.path' but directly the path of a file. In
addition, keyword 'lib' as be replaced by 'path'.
Some changes in setup for PyPi.