Add Filemode to TreeEntry

This field was missing, so let's add it, and let's add the const
definitions for the modes while we're here.

object_test.go

@@ -33,10 +33,15 @@ func TestObjectPoymorphism(t *testing.T) {
 		t.Fatalf("Converting back to *Tree is not ok")
 	}
 
-	if tree2.EntryByName("README") == nil {
+	entry := tree2.EntryByName("README")
+	if entry == nil {
 		t.Fatalf("Tree did not have expected \"README\" entry")
 	}
 
+	if entry.Filemode != FilemodeBlob {
+		t.Fatal("Wrong filemode for \"README\"")
+	}
+
 	_, ok = obj.(*Commit)
 	if ok {
 		t.Fatalf("*Tree is somehow the same as *Commit")

tree.go

@@ -13,6 +13,15 @@ import (
 	"unsafe"
 )
 
+const (
+	FilemodeNew            = C.GIT_FILEMODE_NEW
+	FilemodeTree           = C.GIT_FILEMODE_TREE
+	FilemodeBlob           = C.GIT_FILEMODE_BLOB
+	FilemodeBlobExecutable = C.GIT_FILEMODE_BLOB_EXECUTABLE
+	FilemodeLink           = C.GIT_FILEMODE_LINK
+	FilemodeCommit         = C.GIT_FILEMODE_COMMIT
+)
+
 type Tree struct {
 	gitObject
 }
@@ -21,6 +30,7 @@ type TreeEntry struct {
 	Name string
 	Id  *Oid
 	Type ObjectType
+	Filemode int
 }
 
 func newTreeEntry(entry *C.git_tree_entry) *TreeEntry {
@@ -28,6 +38,7 @@ func newTreeEntry(entry *C.git_tree_entry) *TreeEntry {
 		C.GoString(C.git_tree_entry_name(entry)),
 		newOidFromC(C.git_tree_entry_id(entry)),
 		ObjectType(C.git_tree_entry_type(entry)),
+		int(C.git_tree_entry_filemode(entry)),
 	}
 }