Code: Add optical flow scale factor state and change optical flow fusion

Uses optical flow LOS rate data that are not body rate compensated
Adds State for optical flow scale factor
Range finder fusion is working

Note: Optical flow fusion is not working although all fucntionality is in place
There is an error in the predicted flow values that needs to be fixed.
Flow measurement state and covariance updates have been inhibited by setting a 0
innovation consistency gate
Derivations: Fix sign error in optical flow LOS rate measurement equations
Code: Corrected bugs in optical flow fusion prediction
Code: bugfixes and modifications to optical flow fusion

The scale factor and other state estimates still destablise during flight

Further experiments with  removing optimisations in range fusion are
required.
Derivations: Updated 23 state loosely couple derivation to improve efficiency and correct sign error