kalman filter on 6dof robot motions

[ahundt]

reference projects worth a look:

• https://github.com/mherb/kalman
• https://github.com/mherb/kalman/tree/master/examples/Robot1
• https://github.com/jeremy-shannon/CarND-Extended-Kalman-Filter-Project
• https://github.com/priseborough/InertialNav
• https://github.com/sfwa/ukf/blob/master/examples/sfwa_ukf/cukf.cpp
• https://github.com/ckirksey3/extended-kalman-filter-cpp