new cookie implementation

In previous versions cookies were implemented according to Netscape or RFC 2109.
As RFC 2109 was obsoleted twice by RFC 2965 and RFC 6265, I made changes to implement RFC 6265 instead. Netscape cookies are still handled.
The chosen algorithm is the permissive one as described in RFC 6265. Then we can deal with more servers/proxies.
This change is for v0.120b and following.