Add support pcl::PointXYZRGBA to pcl::VLPGrabber. Deprecate rgb signatures.

[UnaNancyOwen]

Add support pcl::PointXYZRGBA to pcl::VLPGrabber.
This change will be able to attach color to point cloud using pcl::visualization::PointCloudColorHandlerRGBField.

This pull request is a re-send #1738.
Please check the discussion about this pull request.
Thanks,

[taketwo]

This method is shadowed in the deriving class. This is a recipe for troubles!
Suppose you have HDLGrabber* grabber = new VLPGrabber;.
What do you think grabber->getMaximumNumberOfLasers() will return?

Please change into virtual const.

[SergioRAgostinho]

Suppose you have HDLGrabber* grabber = new VLPGrabber;

I argue that that use case is not really applicable given the current inheritance scheme (poorly implemented).

Edit: Then again, your suggestion prevents even more poop to happen on an already poopy situation.

[taketwo]

Well, I did not invent this, this is exactly use-case Tsukasa proposed: #1738 (comment)

[UnaNancyOwen]

Does your proposal mean this?

- static uint8_t
- getMaximumNumberOfLasers ();
+ virtual uint8_t
+ getMaximumNumberOfLasers () const;

  uint8_t
- pcl::HDLGrabber::getMaximumNumberOfLasers ()
+ pcl::HDLGrabber::getMaximumNumberOfLasers () const
  {
    return (HDL_MAX_NUM_LASERS);
  }

- static uint8_t
- getMaximumNumberOfLasers ();
+ virtual uint8_t
+ getMaximumNumberOfLasers () const;

  uint8_t
- pcl::VLPGrabber::getMaximumNumberOfLasers ()
+ pcl::VLPGrabber::getMaximumNumberOfLasers () const
  {
    return (VLP_MAX_NUM_LASERS);
  }

[taketwo]

Yes

[UnaNancyOwen]

Fixed

[SergioRAgostinho]

@taketwo Do you think it is worth to keep the breaks ABI label even when it is superseeded by the breaks API one? In this case you added it after. What was the rationale behind it?

[taketwo]

API break implies ABI break. Further, ABI changes per se are not interesting for users, it's only for us to know if version number needs to be bumped. In this sense yes, ABI break tag is redundant. I don't remember what my rationale was, but from now on we can agree that ABI tag is not needed if there is API tag already.

[SergioRAgostinho]

Removing API breakage tag based on #2396 (comment) and #2396 (comment).

[SergioRAgostinho]

Can be considered API breakage because we renamed protected members. If people derive from the class their code will break. Namely current_scan_xyzrgb_, current_sweep_xyzrgb_, scan_xyzrgb_signal_ and sweep_xyzrgb_signal_.