Add cookie convenience funcs

Fix test helper func

libkiwi.go

@@ -18,6 +18,8 @@ const _USER_AGENT = "Mozilla/5.0 (Windows NT 6.1; rv:60.0) Gecko/20100101 Firefo
 type KF struct {
 	client http.Client
 	domain *url.URL
+
+	Cookies jar
 }
 
 // Supply your own http.Client to route through any proxies.
@@ -37,8 +39,9 @@ func NewKF(hc http.Client, host *url.URL) (KF, error) {
 	}
 
 	return KF{
-		client: hc,
-		domain: u,
+		client:  hc,
+		domain:  u,
+		Cookies: jar{hc.Jar},
 	}, nil
 }