Robot component: milestone 2

[fabienrohrer]

Following #800

• device list scroll bar is not good looking, because depending on the OS/browser. We could do better for chrome at least.
• Displaying more meta information could be great, including at least:
  • robot center and orientation
  • distance sensor ray
  • camera frustrums

[fabienrohrer]

• initial position of some robots (especially of the robotis-op2 and bioloiddog) are not good. A solution could be to add some optional initial position in the meta json file.

[fabienrohrer]

• As the robot are static and there is a ground to see the shadows, some robots may intersect with the ground, when moving the sliders.