Registry patch for group read/write permissions

[Lyneira]

Add a registry patch file (based on ServerAliveInterval.reg) with options that set owner/group read,write permissions for new files and owner/group read,write,execute permissions for new directories.

Also update README.md:

• Add dedicated section with the info on how to pass options to sshfs for mapped network drives and "net use".
• Move sshfs option passing info out of Preventing timeouts section.
• Add section on setting looser permissions for new files and directories.

Workaround for #68 and #180.