vfs: Make file handles compatible with OS

* Implement directory handles
  * Unify OpenFile
  * Add all the methods to match *os.File
  * Add StatParent and Rename methods to VFS

vfs/write.go

@@ -2,6 +2,7 @@ package vfs
 
 import (
 	"io"
+	"os"
 	"sync"
 	"time"
 
@@ -10,6 +11,7 @@ import (
 
 // WriteFileHandle is an open for write handle on a File
 type WriteFileHandle struct {
+	baseHandle
 	mu          sync.Mutex
 	closed      bool // set if handle has been closed
 	remote      string
@@ -195,6 +197,11 @@ func (fh *WriteFileHandle) Release() error {
 	return err
 }
 
+// Stat returns info about the file
+func (fh *WriteFileHandle) Stat() (os.FileInfo, error) {
+	return fh.file, nil
+}
+
 // Close closes the file calling Flush then Release
 func (fh *WriteFileHandle) Close() error {
 	err := fh.Flush()