* dnsfilter: use golibs/cache

+ config: add cache size settings
+ config: add cache_time setting

dnsforward/dnsforward_test.go

@@ -491,6 +491,11 @@ func createTestServer(t *testing.T) *Server {
 	s.conf.FilteringConfig.SafeBrowsingEnabled = true
 	s.conf.Filters = make([]dnsfilter.Filter, 0)
 
+	s.conf.SafeBrowsingCacheSize = 1000
+	s.conf.SafeSearchCacheSize = 1000
+	s.conf.ParentalCacheSize = 1000
+	s.conf.CacheTime = 30
+
 	rules := "||nxdomain.example.org^\n||null.example.org^\n127.0.0.1	host.example.org\n"
 	filter := dnsfilter.Filter{ID: 0, Data: []byte(rules)}
 	s.conf.Filters = append(s.conf.Filters, filter)