applyHardCollision() now takes a CollisionInfo rather than two vectors ("penetration" and "addedVelocity")
ParticleTreeElement::_particles is now a QList<> instead of std::vector<> for faster erase()
Removing per-particle calls to usecTimestampNow() which can add up when simulating a lot of particles.
Removing one more usecTimestampNow() call in Particle::update()
Fixing measure of "old" particles while simplifying the math (faster!).
Modifying how the "particle is stopped" logic reads with minimal modification to how it works.
Adding static friction for easier "catching" of particles on paddle hands.
Merge branch 'master' of ssh://github.com/highfidelity/hifi into paddle-fixes-2
Merge pull request #1598 from AndrewMeadows/paddle-fixes-2

Paddle fixes 2
Merge branch 'master' of git://github.com/worklist/hifi into new_particle_scripting_interface

Conflicts:
	libraries/particles/src/Particle.cpp
	libraries/particles/src/ParticleCollisionSystem.cpp
	libraries/particles/src/ParticleTreeElement.cpp