more efficient Particle.sleepTick() function and fixed Particle.timeLastSleepy update bug
version bump
changed version in package.json
reuse of pre- and post-step event objects in World
changed world reference to this in World
only compute gravity norm once in World.step()
small code fixes
GC optimizing the TimeSeries for profiling plot
reuse of temp solve vectors
reuse equations array in solver
Merge branch 'dev' of https://github.com/schteppe/cannon.js into dev

Conflicts:
	build/cannon.js
	build/cannon.min.js
	src/objects/Particle.js