Method to integrate liosam as an odometry source

[abhi2198]

I have been working on this for a bit; for anyone needs to use lio sam as an odometry method.
Still a work in progress.
https://github.com/abhi2198/rtabmap-liosam
Separated out ros from lio_sam https://github.com/abhi2198/liosam_nodelets

[matlabbe]

Thanks for sharing! I suggest to open a fork on rtabmap repo and apply your changes in that fork, that will be easier to see what is different from the original code. I don't know how deep the changes are, but if it is mostly OdometryLIOSAM class where all the changes are, we could integrate the changes with a pull request if you want.

[abhi2198]

@matlabbe Here is the fork and diff abhi2198@0ceab52 . I will PR this once I'm done with clean up and minor fixes.