RealFlight: update Griffin model gimbal

[rmackay9]

This updates the Arace Griffin quadplane's gimbal.

The changes are below but the intention is to change the 3-axis brushless gimbal's yaw control so that by default it works in vehicle body-frame instead of earth-frame. I think this is a more common setup than what it has now which is earth-frame.

SUBGROUP[#167]
     GimbalFollowYaw=BOOL:Yes
     GimbalYawReverse=BOOL:No

This is the first time I'm updating a model but I tried to be careful to only make the above changes. The way I did this was:

• Select Model > Custom Aircraft > Griffin
• Select Model > Edit Aircraft > Griffin
• File > SaveAs > Griffin-gimbal-fix
• made the two changes mentioned above
• Closed the window, replied "yes" to "save this model"
• Simulation > Export > Entire Aircraft > Saved overtop of the Griffin_EA.RFX file

I also updated the corresponding parameter file so that SERVO3_REV is false to fix the direction of rotation of the gimbal.