Some work on identifiers

IAuthenticationHandler should now implement an Id that can be used by
both the server and client handlers.
Renamed MultiAuthenticationHandler to CompositeAuthenticationHandler -
More fitting.
Implemented Ids on Password Auth.
Added modules for both client and server password authentication
(Pre-Shared secret).
Removed obsolete / Unused files

Username / password auth is being merged in to the more general
AuthenticationModule.
Lynxification

We need more of this.
'Fixed build'
Added username / password auth skeleton

Skeleton for username / password authentication
Renamed Composite auth handler

Renamed IMultiAuthenticationHandler to ICompositeAuthenticationHandler
(Consistency!)
Added AuthModuleBase (NYI)
AuthModuleBase implementation

Base class for auth modules implemented.