Colored point clouds

[carlosmccosta]

Please consider publishing point clouds with the color / grayscale information.
Most if not all 3D cameras that have this information publish it alongside the 3D point data.
This is trivial to implement on the phoxi_camera and is much user friendly to the end users than forcing them to subscribe to a image and xyz point cloud.
The end users should not have to deal with the particular technology of a 3D sensor.
For PhotoNeo, the correspondence between a 3D point and its gray pixel is direct, but for other types of 3D sensing it might not be trivial to do or might be proprietary and not available to the end users.
As such, this should be done on the camera driver and not by the end users (most end users want to have the ability to change the 3D sensor without having to change their 3D perception implementation).

Please take a look at my fork, I have already implemented this feature:
https://github.com/carlosmccosta/phoxi_camera/commits/master-all-pr
#21
#24