Moved pose_2d_ekf component to fmProcessors/localization_mapping
Added documentation of VectorNav VN-100 parameters to test launch file.
Changed default gyro axis in example launch file for differential_odometry_node
Corrected a minor problem in differential_odometry_node causing a warning "IMU data not available" when using imu_orientation as input.
Added pose_2d_ekf to fmProcessors