add level from string

level.go

@@ -1,6 +1,7 @@
 package logb
 
 import (
+	"strings"
 	"sync"
 )
 
@@ -61,3 +62,13 @@ func (l Level) String() string {
 	}
 	return s
 }
+
+func LevelFromString(s string) Level {
+	s = strings.ToUpper(s)
+	for _, l := range []Level{ERROR, WARN, INFO, DEBUG, VERBOSE} {
+		if l.String() == s {
+			return l
+		}
+	}
+	return INFO
+}