Merge branch 'master' into enhancement/locomotion

.circleci/config.yml

.env.defaults

.travis.yml

README.md

doc/image_orientations.gif

package-lock.json

package.json

src/assets/LoadingObject_Atom.glb

src/assets/environments/environments.js

src/assets/hud/spawn_pen-hover.png

src/assets/hud/spawn_pen.png

src/assets/hud/spawn_photo-hover.png

src/assets/hud/spawn_photo.png

src/assets/images/cubemap/negx.jpg

src/assets/images/cubemap/negy.jpg

src/assets/images/cubemap/negz.jpg

src/assets/images/cubemap/posx.jpg

src/assets/images/cubemap/posy.jpg

src/assets/images/cubemap/posz.jpg

src/assets/stylesheets/2d-hud.scss