[PATCH 4/4] Add a MessageWaiting interface to track message waiting indications.

[Denis Kenzior]

Hi,

I've pushed this patch and heavily customized it afterwards to simplify the 
logic a bit.  Can you check that it is still working as intended?

Writing of MBDN fields is still missing.  Can you send another patch for this?  
Also one fo writing of MSISDN records in SimManager would be good as well.

Regards,
-Denis