Improve Rviz plugin usability and performance

[victorreijgwart]

This PR proposes a full rewrite of the Rviz plugin, to improve performance and ease of use.

New features:

• Communication
  • Incremental transmission of the map (avoids exceeding ROS message size limits for very large maps)
  • Rewritten map<->ROS msg conversions, matching the new map<->byte stream implementation
• Rviz plugin UI
  • Support different render modes (slice; grid) in a single WavemapDisplay instance
  • Each render mode can be configured through its own foldout menu
  • The map is only stored once per plugin instance and shared among the render mode handlers
  • Grid render mode
  • Expose grid color options in the UI
  • Add option to set maximum grid drawing resolution
    • E.g. to improve frame rate when displaying large maps on computers with no GPU
  • Improve default settings s.t. it can be used with minimal tuning in most scenarios
• Performance improvements
  • Only redraw map blocks that changed
  • Render grid blocks with Level of Detail based on their distance to the camera
  • Use a work queue and limit the update time per frame, to avoid stalling Rviz when large map changes occur
  • Interface directly with Ogre, instead of using rviz::Pointcloud as an intermediary for rendering

Removed features:

• Remove the option to render map meshes
  • This render mode does not yet produce good iso-surfaces and is currently very slow. It will be reintroduced once its more mature.

[victorreijgwart]

Testing with GCC's Thread Sanitizer is currently failing in GitHub actions, as the linker fails to find libtsan_preinit.o. The file seems to have disappeared in a recent update. The issue is reproducible on local machines running 20.04 with up-to-date apt packages.

The issue matches this Ubuntu bug report: https://bugs.launchpad.net/ubuntu/+source/gcc-10/+bug/2029910

Hopefully, it will be fixed soon. Otherwise the best option is probably to ignore TSAN and move ahead with the merge once I addressed your comments. This should be safe given that this PR introduces no threading related changes.

[victorreijgwart]

/prepare-release minor

[victorreijgwart]

Have a quick look over the comments I've added but otherwise looks good to me.

Thanks for reviewing!