Changed argument names in collision methods for improved readability.
Name changes, formatting, and comments for readability.
Moved ParticleTreeUpdateArgs into ParticleTreeElement.h
Pulling latest worklist/hifi into local repo
Pulling latest worklist/hifi into local repo
pulling latest upstream changes to local repo
Adding Particle::_mass and correct elastic collisions between particles
Temporarily disabling DAMPING and non-unity ELASTICITY during particle-particle collisions
merge of latest upstream work in preparation for pull request #1500

Conflicts:
	libraries/particles/src/ParticleCollisionSystem.cpp
Merge pull request #1502 from AndrewMeadows/master

more correct particle-particle collisions