Changes the pose publishing to always publish the odom to map transform.
Either expects or provides (configurable) the odom to tracking transform.
Also cleans up the RViz plugin code a bit.
* Add code to allow offline processing of 2D Cartographer bags.
Fixes waiting for transforms to be published, adds support for multi-echo
laser scans, sets default values for the submap topic and query for the
RViz plugin.