module documentation

Cred errors.

Class LoginDenied The realm rejected this login for some reason.
Class LoginFailed The user's request to log in failed for some reason.
Class Unauthorized Standard unauthorized error.
Class UnauthorizedLogin The user was not authorized to log in.
Class UnhandledCredentials A type of credentials were passed in with no knowledge of how to check them. This is a server configuration error - it means that a protocol was connected to a Portal without a CredentialChecker that can check all of its potential authentication strategies.