Attempted fix at the umask problem

It NEARLY works.

The problem is that it fails when creating directories with permissions... As the native Unix filesystem does respect the umask even in this case, I've tried to emulate that. Works everywhere except for directories.

So, maybe not to merge.

Anyway, the core of the matter is that with this patch set, umask plays its role: that of _undoing_ permissions the user wants to grant.