[api][feat] Change SLAM point Definition

1. We want to take advantage of the left space in point structure adding input information. Added fields are device_id and label
2. Intensity field is usually float at the drivers output so we change its current type to fit this format
3. The point name is changed so it is not related to the fields anymore
4. The hierarchical structure is no longer necessary and add unecessary copies

Changes :

1. Change LidarPoint.h
   • intensity field becomes float
   • New fields device_id and label are added
   • Point type name is changed to PointSLAM
2. Consequently update all files
   • SLAM files using PointSLAM and label_id
   • slam_config.yaml file comments to describe PointSLAM
   • ros_wrapping file using PointSLAM and label_id
   • vtkSlam file laser_id

@nicolas.cadart @nick.laurenson