NavFilter : Added supporting files
NavFilter : Added ReadMe.txt
NavFilter : Updated Test Log Files
Update ReadMe.txt
Update ReadMe.txt
ReadMe.txt updated
Derivations : Add files used to derive algebraic expressions
Merge branch 'master' of github.com:priseborough/InertialNav

# By Paul Riseborough
# Via Paul Riseborough
* 'master' of github.com:priseborough/InertialNav:
  ReadMe.txt updated
  Update ReadMe.txt
  Update ReadMe.txt
ReadMe : Typographical errors corrected
NavFilter : Flexibility and robustness improvements

Added ability to turn off use of compass and/or airspeed data to support use where
these sensors are not fitted.
Added protection to prevent long term loss of GPS causing uncontrolled position error
covariance growth
Update GenerateEquations.m
Magnetometer Fusion : Optimisation of the (I - KH)P step
An optimised multiplication routine taking advantage of the zero columns in the K.H product
as used to significantly reduce the cost of the covariance update
Merge branch 'master' of github.com:priseborough/InertialNav

# By Paul Riseborough
# Via Paul Riseborough
* 'master' of github.com:priseborough/InertialNav:
  Update GenerateEquations.m
Preliminary Load Calc for PX4
Added functionality for finer adjustment of time delay compensation
PlotNavFilterData.m : Fixed unwanted command echo
Nav Filter : Fixed initial covariance bug on wind-speed states

Wind-speed covariance was being set to zero rather than frozen when on ground. This caused
slow wind sped identification.
Result plots generated  generated using TestLog3.mat
Magnetometer Data Fusion : Spread fusion across three prediction time steps

Magnetometer data fusion is the most expensive computationally of all the steps. This
modification performs fusion of the the X,Y and Z components across three prediction time cycles. This reduces  loading on a prediction + magnetometer fusion time step by
~14000 operations
Velocity and Position Fusion : Added more robust data validity checks

The checks are now applied to position or height or velocity as measurement groups, and
a retry time has been added to each group to force a fusion if more than a specified number of seconds without fusing measurements.