Add a function to retrieve a log level by name (useful for config)

logging_test.go

@@ -0,0 +1,15 @@
+package logging
+
+import "testing"
+
+func Test_LevelByName(t *testing.T) {
+	for _, levelName := range levelNames {
+		l, e := LevelByName(levelName)
+		if e != nil {
+			t.Errorf("level %s not recognized", levelName)
+		}
+		if l.Name() != levelName {
+			t.Errorf("expected '%s', got '%s'", levelName, l.Name())
+		}
+	}
+}