Addition of custom graphing fields and scaling

This release adds the following features
1.Scaling of rcCommand to deg/s using Betaflight v2.6.1 scaling.

• The table below the graph now shows the deg/s value for rcCommand (roll, pritch and yaw).
• The rate values for pitch, roll and yaw from the configuration that the log refers to needs to be entered into a new Log Setup dialog before opening the log file. (one day these rates might be added to the blackbox log file header - like rcRate at the moment).

2.Once we know the rcCommand deg/s values, we can now generate 9 new graph fields. These are at the end of the list when setting up graph fields.

• PID_Error[roll], PID_Error[pitch], PID_Error[yaw];
  is a graph of the error the PID is using to calculate motor outputs; the closer to the center line this graph is, the better the tuning (?); the error is the difference between the commanded rcCommand (in deg/s) and the actual gyro (in deg/s).
• rcCommand__s_[roll], rcCommand__s_[pitch], rcCommand__s_[yaw]_; and
• gyroADC__s_[roll], gyroADC__s_[pitch], gyroADC__s_[yaw]_;
  these are both (rcCommand and gyroADC) scaled to the same range (0-1200deg/s) so in an ideal world, when plotted together (rcCommands[roll], and gyroADCs[roll] for example) they would perfectly overlap; any difference (PID_Error) is what the PID controller works on to correct the crafts attitude.

SCALING ONLY WORKS ACCURATELY FOR REWRITE AND LUXFLOAT (MW23 for a future release) HOWEVER THIS VIEWER CAN STILL BE USED FOR ALL LOGS.