syssetup - Improve password checking

PLEASE READ BEFORE CLOSING! Even though I understand that user passwords have not been fully implemented, this patch implements password checking. The features found in the patch, by default, have been disabled for now to make it easier for developers to test ReactOS without having to deal with any of those dialogs every single time. But at the same time, make it so they could be easily enabled for release versions.

Changelog:

• If the password is empty, refuse the user to go on until they do so. This option can be enabled in settings.h.
• Implement the password strength dialog box like the one found in Server 2003. Right now, this feature is only partially implemented. The only checks that are implemented is password length, and making sure the password is not the same as the username. This option can also be enabled in settings.h.
• Allow the downloading of Gecko to be disabled from settings.h. This is enabled for now since other people may use it.