Oid: remove Bytes()

This is not needed. We can do id[:] to get a slice.

git.go

@@ -28,7 +28,7 @@ func init() {
 	C.git_threads_init()
 }
 
-// Oid
+// Oid represents the id for a Git object.
 type Oid [20]byte
 
 func newOidFromC(coid *C.git_oid) *Oid {
@@ -72,10 +72,6 @@ func (oid *Oid) String() string {
 	return string(buf)
 }
 
-func (oid *Oid) Bytes() []byte {
-	return oid[0:]
-}
-
 func (oid *Oid) Cmp(oid2 *Oid) int {
 	return bytes.Compare(oid[:], oid2[:])
 }