OpenDAFF license changed to Apache License Version 2.0

After discussion with the inventor of OpenDAFF, I have changed the license to the less restrictive Apache License Version 2.0, which also allows the use of the OpenDAFF library in commercial products.

See: http://www.opendaff.org

I am going to license all my code base with this license as it is very user friendly and might allow for further development at a company even after leaving the academic environment. This way, commercial partners and the academic institutions can both benefit.