WebXR support system for A-frame

XR

• xr/basic source

  Use A-frame to show Hello WebVR in XR

AR

• ar/hit_test source

  Use A-frame to find anchors by searching on tap events

• ar/reticle source

  Use A-frame to have a reticle on AR mode

• ar/light source

  Use A-frame to have a reticle with light estimate on AR mode