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.
Start of C++ conversion
Nav Filter : Added processing to convert IMU data.

Also includes a tidy-up
Magnetometer Data Fusion : Minor Bug Fix

Corrected minor bug that caused magnetic field estimates from the current rather than measurement time coordinate to be used.
Derivation : Cleaned up symbolic derivation script
Derivations : Update to enable auto generation of C language code blocks
Data Loading : Modified to provide angular rates and accelerations and better time data
Derivations : Output Files
Plots : Updates generated from test log 3
Code : Preliminary coding updates
Update ConvertToC.m

Fixed bugs and added conversion for ^2 operators to use the sq() function
Update C_code.txt

Results from updated Matlab to C converter
Update ConvertToC.m

Bugfix
Update C_code.txt

Updated results from Matlab to C code converter
Update C_code.txt

Replaced^(1/2)in one line (by hand)
Update ConvertToC.m

bugfix
Merge branch 'master' of github.com:priseborough/InertialNav

# By Paul Riseborough
# Via Paul Riseborough
* 'master' of github.com:priseborough/InertialNav:
  Update ConvertToC.m
  Update C_code.txt
  Update C_code.txt
  Update ConvertToC.m
  Update C_code.txt
  Update ConvertToC.m
ConvertToC.m : Added conversion for ^(1/2) operator
Measurement Fusion Code Updates
CovariancePrediction.cpp