Added Object interface for Commit, Tree, Blob and Tag

* New Object interface is distinct from core.Object
* New Object interface is used in places where returned object could be of any type
* Object is implemented by Commit, Tree, Blob, File and Tag
* Added Repository.Object function for retrieving objects of any type
* Tag.Object now returns Object instead of core.Object
* Tag target hash is now publicly accessible
* Renamed Tag.Type field to Tag.TargetType, making it distinct from Tag.Type function
* Fixed infinite recursive loop in TagIter.Close
* TreeWalker.Next now returns Object instead of core.Object
* Removed some duplicate test setup code

1 files changed, 2 insertions, 10 deletions

diff --git a/file.go b/file.go
index e3e8e93..76ec962 100644
--- a/file.go
+++ b/file.go
@@ -3,8 +3,6 @@ package git
 import (
 	"bytes"
 	"strings"
-
-	"gopkg.in/src-d/go-git.v3/core"
 )
 
 // File represents git file objects.
@@ -64,15 +62,9 @@ func (iter *FileIter) Next() (*File, error) {
 			return nil, err
 		}
 
-		if obj.Type() != core.BlobObject {
-			// Skip non-blob objects
-			continue
+		if blob, ok := obj.(*Blob); ok {
+			return newFile(name, blob), nil
 		}
-
-		blob := &Blob{}
-		blob.Decode(obj)
-
-		return newFile(name, blob), nil
 	}
 }