Create waypoint visualization

[Agustin Alba Chicar]

Create a kind of circle or similar figure on Gazebo to visualize waypoints. The following characteristics should be configurable:

• Position
• Diameter
• Colour

[Agustin Alba Chicar]

@andres_fortier, @JChoclin some improvements to show:

Diameter is still hardcoded and color is not touched through message publishing, but we can improve it.

[Javier Iván Choclin]

Added circles like cylinders through visual messages. refs #7

→ <<cset dec0700214a4>>

[Javier Iván Choclin]

Change the API of waypoints so it's similar to the road. refs #7

→ <<cset 5ec082213151>>

[Javier Iván Choclin]

Modify the API to include the waypoint radius. refs #7

→ <<cset a73b5182c684>>