WIP rewrite the daemon

cmd subdir does not build on purpose, it's only left in tree to grab old
code and move it to github.com/zrepl/zrepl/daemon

daemon/logging/adaptors.go

@@ -0,0 +1,32 @@
+package logging
+
+import (
+	"fmt"
+	"github.com/problame/go-streamrpc"
+	"github.com/zrepl/zrepl/logger"
+	"strings"
+)
+
+type streamrpcLogAdaptor = twoClassLogAdaptor
+
+type twoClassLogAdaptor struct {
+	logger.Logger
+}
+
+var _ streamrpc.Logger = twoClassLogAdaptor{}
+
+func (a twoClassLogAdaptor) Errorf(fmtStr string, args ...interface{}) {
+	const errorSuffix = ": %s"
+	if len(args) == 1 {
+		if err, ok := args[0].(error); ok && strings.HasSuffix(fmtStr, errorSuffix) {
+			msg := strings.TrimSuffix(fmtStr, errorSuffix)
+			a.WithError(err).Error(msg)
+			return
+		}
+	}
+	a.Logger.Error(fmt.Sprintf(fmtStr, args...))
+}
+
+func (a twoClassLogAdaptor) Infof(fmtStr string, args ...interface{}) {
+	a.Logger.Info(fmt.Sprintf(fmtStr, args...))
+}