Don't simulate avatars' models when they're being rendered as billboards.
Closes #2165.
Merge branch 'master' of https://github.com/highfidelity/hifi
Merge branch 'master' of https://github.com/highfidelity/hifi
Merge branch 'master' of https://github.com/highfidelity/hifi
Fix for annoying "QThreadStorage" warning.
Merge branch 'master' of https://github.com/highfidelity/hifi
Merge pull request #2176 from ey6es/master

Don't simulate avatars when they're being rendered as billboards, fix QThreadStorage warning.