Align types: int to unsigned int

Block send SMS until finished operation.
GSM3IO.h. Keeps most of board-dependant pins
Flush buffer after GPRS detach
Delete some references to HardwareSerial.h
Include OFF modem status

libraries/GSM/src/GSM3ShieldV1DataNetworkProvider.cpp

@@ -219,6 +219,8 @@ void GSM3ShieldV1DataNetworkProvider::detachGPRSContinue()
 				}
 			else theGSM3ShieldV1ModemCore.closeCommand(3);
 		}		
+		theGSM3ShieldV1ModemCore.theBuffer().flush();
+		theGSM3ShieldV1ModemCore.gss.spaceAvailable();
 		break;	
 	}
 }