fix help text for password, there is no more max password length.  clean up doxygen for email validate function.

#978610 by daniels, hunmonk: Password field description on user_register form is not correctly modified causing duplicated FAPI element.

#838826 by sudhirporwal, hunmonk: ereg deprecated in PHP 5.3, remove from password checking function.

hide the auth user checkbox on the user edit screen if the user is in the pre-auth role -- reduces UI confusion.

#765994 by hunmonk: Non-authenticated role is hidden in user profile form even when 'Set password' is unchecked

remove unnecessary db_query -- admins validating a user account shouldn't trigger an account login, either.

by hunmonk: add an 'Override destination paramter' setting, enabled by default. this gives admins the option to allow LT to force it's redirect paths over a passed destination parameter. related to solving #604492

#604508 by hunmonk: 'Use two e-mail fields on registration form' setting breaks OpenID registrations. this fixes the LT-related problem, but the openid registration process itself may still be broken -- see #216101

#232467 by mfer, benroot, hunmonk: OpenID logins broken when 'Allow users to login using their e-mail address' setting is enabled.

#492486 by mikehostetler: Array merge of user_register_submit function squashes pre-defined user_register_submit functions.