* Added conditional to keyfile fix code that excludes windows.
* Cleaned up old keyfile permissions fix.
* Added umask (not conditional against Windows, because I don't think that is necessary).
This spits out a warning to the console, but ideally it would also
issue a warning to the GUI for those who didn't start it from the
console. N.B. the warning is a one shot thing, since it fixes the
problem in a way essentially undetectable in the future, so it
should be done right if it is to be done at all.
Maybe we should even disable all keys automatically if the keyfile
is found in an insecure state.
