Change LookAtPosition of Head to the eye level of another avatar,
if looking at another avatar in Application.cpp.

Add eyePosition to Head class and bool isLookingAtOther.. in Application.cpp.
Merge remote-tracking branch 'upstream/master' into eyecontact
Add print statements to debug eyecontact code in Application.cpp.
Merge remote-tracking branch 'upstream/master' into eyecontact
Make lookAtVectors lock on other avatar's eyes if the mouse is over
the other avatar's head.

Add rayIntersectsSphere function to Util. glm::intersectRaySphere was buggy.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Remove random print statements from eyecontact code in Application.cpp
Remove unused #include for glm intersect in Application.cpp
Add condition to updateAvatar() where if another avatar's head is at
the center of the screen, the lookAtPosition is set to the eye level
of that avatar.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Fix style mistakes according to code review for eyecontact code.
Merge pull request #642 from LionTurtle/master

Make lookAtVectors lock on other avatar's eyes if the mouse is over the other avatar's head.