2600: Various improvements to UIConnectors and their handling:
* ServerGlue.cs: Method 'DisconnectUIConnector'
** it didn't have Attribute [WebMethod] and hence couldn't get called from the Client (!), resulting in errors in log files and not-gotten-rid-of UIConnector Objects on the server side!
** it wasn't fail-safe in case the client got closed and Forms were still open, which caused that Method to be called from the Form(s) Finalizer(s) although the Client Session was already gone on the server side.

* ClientGlue.cs: Implement IDisposable correctly! It was done wrongly, meaning Dispose() was called twice in most circumstances!!!

* Did away with the TKeepAlive Class as it is no longer needed - one Thread less on the Client side!
** UIConnectors don't need to be Registered for KeepAlive anymore!
** The TKeepAlive Class got renamed to 'TUIConnectorLifetimeHandling' and now has only one static Method left: 'ReleaseUIConnector' which calls Dispose() on the client-glue Object of the UIConnector.
** The IKeepAlive Interface is no longer needed and got removed, too.

Added more logging to be able to track UIConnector instances better...

http://bazaar.launchpad.net/~christian-k/openpetraorg/20140624_webservices_branch__client_server_fixes/revision/2600