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
Update README.markdown
added cloth example
added indent and globals to .jshintrc
jshint World
removed World.temp
reuse of collide event objects
jshint ContactGenerator
jshint and use of !== instead of < in for loops in ContactGenerator
removed unused ContactPoint class
update readme
jshint NaiveBroadphase
removed NaiveBroadphase.temp, fixed inheritance from Broadphase
jshint Ray