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
Fix for sleeping objects never waking up. Refactored Particle methods into prototypes
Fix for boundingSphereRadius not being a method - added method to get/recalculate bounding sphere radius and store it as necessary
Fix for RigidBody not inheriting Particle properly
Fixed order of build
Updated builds
Merge branch 'dev' of https://github.com/schteppe/cannon.js into dev

Conflicts:
	build/cannon.js
	build/cannon.min.js
	src/objects/Particle.js
Merge pull request #51 from airbaggins/dev

Particle inheritance, rays/bounding-spheres, sleeping objects dying
changed back to the old sleep mechanism since the new stuff made the sleep demo go wrong. Ping @airbaggins
reuse of contacts arrays in step loop
reuse of friction equation arrays in World
reuse of collision pair arrays in step loop
contactgenerator loop optimize
ConactGenerator indent fixes