Also added new property 'additional_data' to message event objects. Changes to this attribute (a dict) are passed on from event to event and are also written to the history db as json string (reading of those values isn't implemented yet).
* resolver does not depend on GTK anymore
* renamed a few modules for consistency
* moved all mocks to lib/
* let client_nb test work again. Was broken here
There are many failing tests, help appreciated :-)
