SFTP Permission Handling

[fyrye]

The SFTP permission support is a bit weird.
It shows owner/group, setgid/setuid bits but FileZilla doesn't support changing or preserving these settings on a file or directory.

For example chmod 2755 or 4755 or 6755 on a folder/file.
Uploading a file with the set(u/g)id permission bit set is not preserved. Or changing the Owner/Group/Other permissions (777-000) will also remove these bits forcing you to launch an external program to set those bits manually.

A switch should be used for SFTP based connections to support Owner/Group changes, as well as the 4th octal permission bit, since FileZilla executes the chmod command it should accept all 4 octal bits, and also support chown/chgrp

Command: chmod x750 "test"
Error: chmod: file mode 'x750' contains unrecognised user/group/other specifier 'x'

FileZilla Client
----------------

Version:          3.5.3

Build information:
  Compiled for:   i586-pc-mingw32msvc
  Compiled on:    x86_64-unknown-linux-gnu
  Build date:     2012-01-08
  Compiled with:  i586-mingw32msvc-gcc (GCC) 4.2.1-sjlj (mingw32-2)
  Compiler flags: -g -O2 -Wall -g -fexceptions

Linked against:
  wxWidgets:      2.8.12
  GnuTLS:         2.10.4

Operating system:
  Name:           Windows NT 6.1 (build 7601, Service Pack 1)
  Version:        6.1
  Platform:       64 bit system