NT security information decoding, NT attributes

[Daniel Roethlisberger]

WinAce has the capability to add NT security information for each file to the archive. For archive forensics, Acefile should be able to decode that information in --headers/dumpheaders() and optionally write it to the filesystem on extraction. Also, on Windows, the file attributes should be restored as far as it makes sense on extraction, perhaps optionally as well.

[Daniel Roethlisberger]

• extract security descriptor from FILE blocks having the respective flag set (how to determine length correctly?)
• on Windows, add restore functionality to extract(), calling SetFileSecurity() through ctypes or PyWin32.

[Daniel Roethlisberger]

Implemented.