doc

reference:
	https://github.com/fdarmon/Generalized_ICP

teaser++:
	https://teaser.readthedocs.io/en/latest/installation.html


other useful online packages:
*) https://github.com/koide3/hdl_global_localization
*) https://github.com/ethz-asl/robust_point_cloud_registration.
*) http://www.open3d.org/docs/release/
		http://www.open3d.org/docs/release/tutorial/pipelines/robust_kernels.html #robust and weighted least squares
		http://www.open3d.org/docs/release/tutorial/pipelines/global_registration.html #ransac + FPFH for global registartion
		http://www.open3d.org/docs/release/tutorial/pipelines/multiway_registration.html #pose graph registratioN!?
		http://www.open3d.org/docs/release/tutorial/pipelines/rgbd_integration.html #TSDFs and yada yada

point-line registration
*) https://github.com/xiaoxiaotao/ceres_lm_pl_icp
*) https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10135/1013509/Which-point-line-registration/10.1117/12.2253692.full?SSO=1