Plane: Enable quadplane dead reckoning navigation to start earlier

[peterbarker]

This reduces EKF errors during transition fromVTOL to FW flight when operating without a GPS fix.

[peterbarker]

Logs reflect the new bit being set, 'though does highlights oddities in setting and unsetting this bit as we go through transitions.

This image shows that the bit has the intended effect of setting fly-forward earlier in the transition from qhover to cruise:

this image (with the bit set,) shows we glitch fly-forward flag to zero in some stage of the forward transition:

[IamPete1]

I think its a good idea, but I think just in transition is is a bit too coarse. Maybe a new method for the the transition class? I think we would be OK to turn on fly forward in the timer stage but maybe not airspeed wait.

[tridge]

test here for bits, please check! https://github.com/tridge/junkcode/blob/master/float_int.c