Fix bug 2200 and bug 2242 in which there were problems with logging in after upgrading if you restarted the server first. The new code is less elegant, but it works correctly. It imposes a database hit on login, but it is cached, so it only is incurred once.
The user-new page called a proc in the authentications package which checked to see if a parameter was set or not. However, in upgraded sites, or if the user had entered a blank entry for the parameter, the proc would bomb. I made the proc more robust by using string is false instead of ![parameter... and also added in a util_user_message to make it more explicit what is happening if you aren't able to register (the behavior was very confusing).