Compute the bone radii from the vertices.  It's more error-prone than I
expected, but it more or less works.
Attempting to rotate longitudinally at elbow, rather than wrist.
That didn't really help.  What did help was simply ignoring the wrist
constraints.
Working on testing the Leap/Hydra hands against the avatar body.
Merge branch 'master' of https://github.com/worklist/hifi
Skip the hands' parents as well as the hands themselves.
Add a scale factor to bone radii.
Missed a scale multiplier.
Option to render collision proxies, more general avatar penetration test, fix
for meshes with only one joint influence.
Test hand against other avatars.
Merge branch 'master' of https://github.com/worklist/hifi
Render the palm collision proxies.
Called addPenetrations wrong.
Basic sphere/capsule-cone penetration test.
Merge branch 'master' of https://github.com/worklist/hifi
Adjust palm collision size, use last free index when ignoring.
Ignore further up the hierarchy.
Merge branch 'master' of https://github.com/worklist/hifi
Merge pull request #1332 from ey6es/master

Tweaks to hand rotation, basic hand/avatar collisions using "capsule cone" proxies.