Create lidar visualization

[iche033]

Create visualizations for lidar data. This can be divided into smaller subtasks:

1. Design public APIs for a lidar visualization class, e.g. LidarVisual. The abstract interface will go in ign-rendering/include/ignition/rendering/ and a base implementation will live in ign-rendering/include/ignition/rendering/base
2. Port the LaserVisual class from gazebo to ign-rendering/ogre. This would be the ogre 1.x implementation. Note that in gazebo's LaserVisual class, the data come from ign-transport but since ign-rendering does not use ign-transport, we should design the APIs in 1. to support accepting and modifying lidar data, e.g. either an API that takes a vector of floating point values or individual values. We will call these APIs from ign-gazebo to feed it the lidar data to be visualized.
3. Add ogre 2.x implementation

[mihirk284]

@chapulina Can you please assign this issue to me?

[chapulina]

Done, thanks!

[mihirk284]

Additional Task:-

• Add option to change the visual types to Lines and Points
• Adding colour to visualised point

[chapulina]

Sorry, I think this was closed because I linked it to #116, but that was probably not the intention. Reopening just in case.