This adds an option to subdivide sensor_msgs/LaserScan and
sensor_msgs/MultiEchoLaserScan messages into multiple point
clouds. For slow spinning laser scanners this allows unwarping
using googlecartographer/cartographer#408.
Change googlecartographer/cartographer#248 introduced a separation
between MapBuilder and TrajectoryOptions. The ROS repositiories require
changes to track this modification.
* Pulls out TfBridge.
* SensorBridge has its own options.
* SensorBridge is now responsible for transforming the sensor data into the tracking frame.
* Constant odometry covariance is no longer optional.