v0.4

Majors changes :

• Added the possibility to pass a callback to char_by_char and word_by_word methods. The callback being executed after the delay between each character and word respectively.
• Added the possibility to pass arguments to callback passed to char_by_char and word_by_word methods (via the parameter cargs which accept an infinite number of arguments).
• DialogBox class is now context manager (see this example for more information).

Minors changes :

• Added some comments in the source code.