[MAJOR] Implement detection of (and, if possible, protection from) stealth-ping SMS messages

As per the standard, SMS with TP-PID 64 in its PDU must force the phone to indicate its reception to SMSC but must leave no indication or trace on the phone.

For the sake of privacy, we need to disable processing all incoming messages with TP-PID different from 0 and 50. If it's not possible (e.g. if the implementation of this is placed into the Qualcomm baseband), we must at least indicate the fact that such a message was received.

Test condition PDUs are to follow.