Enabled assertion on content_negotiation during autotests
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"
Updated content_negotiation with better class names and feature names.
Minor semantic changes in VARIANTS classes
Factorized some code in HTTP_ACCEPT_LANGUAGE
Class renaming for content_negotiation
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
Updated README.md for conneg
Using the new Content Negotiation library to implement WSF_REQUEST.is_content_type_accepted
Fixed an issue with one short chunk and empty trailer

issue#81
Fixed issue related to {WSF_WGI_DELAYED_HEADER_RESPONSE} and filter response like the logger response wrapper.

issue#82
Reintroduced WSF_SERVICE.to_wgi_service: WGI_SERVICE
since it was used in the "WSF" test cases.
Minor changes in wsf test cases.
Added content_negotiation in "wsf" library
Merge branch 'master' of github.com:EiffelWebFramework/EWF
Merge branch 'content_nego_review'

Conflicts:
	library/network/protocol/content_negotiation/src/conneg_server_side.e
	library/network/protocol/content_negotiation/src/parsers/common_accept_header_parser.e
	library/network/protocol/content_negotiation/test/conneg_server_side_test.e