Add support for performance data

[Rodemfr]

According to T110 documentation, there is the possibility to display performance data on some Micronet displays (T110, T113 & T210). It is strongly suspected that these data come from Raymarine proprietary NMEA sentence $PTAK and sent to Micronet via T122 or Micro-Talk.
It would be great if we could discover these performance data field by spying a T122 with MTN.
The setup would be to use qtVlm to generate the $PTAK sentences to T122 and to spy Micronet messages from T122 with MTN.

Here are a few information on $PTAK :

First I see a initial burst of $PTAK sentences which are sent only once and which seem to define what are the 6 parameters which will be sent periodically :

$PTAK,FFP1,%POLAR,   %*23
$PTAK,FFP2,TSPEED,   %*56
$PTAK,FFP3,=ANGLE,  @*7D
$PTAK,FFP4,=TACK,   @*06
$PTAK,FFP5,STREAM,  KTS*17
$PTAK,FFP6,STREAM,   @*38

Then periodically, $PTAK is used again to send the data :

$PTAK,FFD1,123*4B
$PTAK,FFD4,320*4F
$PTAK,FFD3,175*4A
$PTAK,FFD2,172*4C
$PTAK,FFD5,0*4F
$PTAK,FFD6,130*4E

The FFP (page) sentence is transmitted once every 25 seconds, and defines the 6 character header and 6 character footer displayed on each page. The FFD (data) sentence is transmitted once a second, and defines the data to be displayed on the page. So decoding your sentences:

$PTAK,FFP1,%POLAR, %*23 Page 1 header "%POLAR", footer " % "
$PTAK,FFP2,TSPEED, %*56 Page 2 header "TSPEED", footer " % "
$PTAK,FFP3,=ANGLE, @*7D Page 3 header "=ANGLE", footer " ° "
$PTAK,FFP4,=TACK, @06 Page 4 header "TACK ", footer " ° "
$PTAK,FFP5,STREAM, KTS17 Page 5 header "STREAM", footer " KTS "
$PTAK,FFP6,STREAM, @*38 Page 6 header "STREAM", footer " ° "