Add some chairs to sit down

[vincentfretin]

• Add some chairs in the scene with a-waypoint primitive, as a child of an entity with a seat glb.
• Sitting position for the avatars

Related issues:

• a-waypoint primitive c-frame/aframe-gltf-model-plus#43
• Go to the waypoint specified in the url hash c-frame/aframe-gltf-model-plus#42
• move-to-unoccupied-waypoint on naf connected event c-frame/aframe-gltf-model-plus#41

[vincentfretin]

I already added the unoccupyWaypoint() calls in 48de641 for compatibility with waypoints from gltf-model-plus component.

[vincentfretin]

It may be good as an example to create a custom component that creates a grid of chairs specifying number of rows and number of chairs per row, creating a waypoint on it with unique networked id, and using instanced-mesh for all the chairs.

[vincentfretin]

I added avatarPose seatRotation properties on player-info component in 8d850a6 but this is not currently used. I need to open source some other code to use those properties.