[win32] Implement new Win32SMBDirectory

Reimplementation of SMB Directory for win32
Based on new Win32Directory, with same basic features, like hiding elements starting from dot.
Additionally:
* Added a lot of error checks and reporting, 
* Fixes of using UTF-8 strings as win32 ANSI strings, 
* Implemented enumeration of hidden shares, 
* Better deal with authentification
* Properly call win32 network funtions
Not a big deal, but it's helpful IMO to set all pointers to NULL to begin with (even when they're guaranteed an assignment, which this one isn't (but isn't used in the case assignment doesn't occur)