client: Volume class:

- Adjusted to recent metadata cache optimizations (return ENOENT if entry not in cached directory; skip setAttr() if no attributes will be changed)
- Add stat for hard links from retrieved directory listing if they are the "." or ".." entry.
- Added OpenFile() method which allows to set Windows attributes at file creation.
- Fixed Visual Studio compilation warnings.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3575 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534