Merge pull request #64 from skipor/support_func_decode

Support func decoding via hooks

mapstructure.go

diff --git a/mapstructure.go b/mapstructure.go
index 40c0f38..bd46603 100644
--- a/mapstructure.go
+++ b/mapstructure.go
@@ -202,7 +202,7 @@
 			d.config.DecodeHook,
 			dataVal.Type(), val.Type(), data)
 		if err != nil {
-			return err
+			return fmt.Errorf("error decoding '%s': %s", name, err)
 		}
 	}