* querylog: move code to a separate package

+ config: "querylog_interval" setting
/control/querylog_config, /control/querylog_info
+ POST /control/querylog_clear

querylog/querylog.go

@@ -0,0 +1,33 @@
+package querylog
+
+import (
+	"net"
+	"time"
+
+	"github.com/AdguardTeam/AdGuardHome/dnsfilter"
+	"github.com/miekg/dns"
+)
+
+// QueryLog - main interface
+type QueryLog interface {
+	Close()
+
+	// Set new configuration at runtime
+	// Currently only 'Interval' field is supported.
+	Configure(conf Config)
+
+	Add(question *dns.Msg, answer *dns.Msg, result *dnsfilter.Result, elapsed time.Duration, addr net.Addr, upstream string)
+	GetData() []map[string]interface{}
+	Clear()
+}
+
+// Config - configuration object
+type Config struct {
+	BaseDir  string // directory where log file is stored
+	Interval uint32 // interval to rotate logs (in hours)
+}
+
+// New - create instance
+func New(conf Config) QueryLog {
+	return newQueryLog(conf)
+}