==============
* Remove ``_headers`` property to browser object, the headers manipulation functions now impact directly the
``Browser.session.headers`` dict
* Since ``headers`` keyword argument isn't called anymore, you can add specific headers for a single request
* Add a better history support. The history is now an object and has a previous and a forward methods, see the docs for
all informations
* User can define history object base on the `BaseHistory` class
* Improve tests for new history
* Updated documentation for history
Backward compatibility breaks :
* the private property ``_headers`` no longer exists
* the ``back`` parameter for the ``open_url`` method has been removed