Splitted SERVER_CONTENT_NEGOTIATION in 4 differents classes for each kind of negotiation
Changed to use ITERABLE over LIST for supported variants arguments
Factorized some code for http parameter parsing such as q=1.0;note="blabla" and so on
Integrated within EWF
The tests project is now void-safe
Using force instead of put_left seems to work fine
and is better for performance,
and no need to check for precondition "not before"
