Further develop PcFcbDisplayTool

[stenbergd]

• Do not use the "start sampling" commands, rather use "get-states p\r" etc at every sample instance. The start sampling commands may be removed from FCB soon.
• Support more data plotting of motor values, reference signals, control output, receiver etc. Perhaps use cool bar diagrams for motor.
• Modify the protobuf header reading to new specification that will be developed for FCB: [ID 1 byte][Len 2 byte][Data]\r\n. Review how this is parsed by current solution (shouldn't look for last \r\n since this may be included in the encoding).
• Need for two threads? One for sending new messages, one for reading back and parsing data?
• Run it on the landing pad Raspberry Pi and visualise data on a nearby screen

[stenbergd]

Done most of the above and fixed various issues in the dev/pcfcbdisplaytool branch

New TODO:

• Plot reference and control (eg thrust, roll mom) signals (Will need new proto message?)
• Investigate "write timeout", is it in FCB code or in Linux driver or PcFcbTool
• Use the semaphore for plotUpdate function