Dead reckoning standalone node.

[bsb808]

Adds a standalone ROS node to emulate the dead reckoning of the for a glider. Implements the algorithm and addresses https://github.com/Field-Robotics-Lab/glider_hybrid_whoi/issues/3

Theory of Operation

• Subscribes to GPS, IMU and pressure sensor publications
• Publishes a lat/lon estimate using a NavSatFix message
• When there is a GPS fix, just reports that fix (no filtering)
• When there is no GPS fix, uses the dead reckoning algo. from https://github.com/Field-Robotics-Lab/glider_hybrid_whoi/issues/3

Initialization and usage parameters are illustrated in the deadreckon.launch file.

How to test/demo

1. Start simulation: roslaunch glider_hybrid_whoi_gazebo start_demo_kinematics.launch
2. Start the node: roslaunch glider_deadreckoning deadreckon.launch

The current simulation example doesn't seem to have a pressure sensor, so the dead reckoning isn't exercises (the velocities are all zero. Would need to have a pressure/depth sensor input to verify the algorithm.