* fixed multi-cookie handling in client request to allow clean deletion
in insert+indirect mode. Now, only the server cookie is deleted and not
all the header. Should now be compliant to RFC2109.
* added a "nocache" option to "cookie" to specify that we explicitly want
to add a "cache-control" header when we add a cookie.
It is also possible to add an "Expires: <old-date>" to keep compatibility
with old/broken caches.
* some doc and examples cleanups
