Merge branch '1.0.0-rc1'
optimization for array clearing

http://jsperf.com/array-destroy/87
force canvas to draw image at specified size
fix package.json
change init root to window
safer window context fix
verlet integrator was misidentified as the improved euler integrator
Merge pull request #98 from slacktracer/master

verlet integrator was misidentified as the improved euler integrator
fix issue #99
fix for issue #94
continuation of fix for issue #99
documentation fix for #104
fix interpolation rendering on follow
support multi-touch
check for body first
added integrator testing sandbox
feature added velocity-verlet integrator
bug fix: multiple calls to ticker.start fixed.

ticker starts automatically
re issue #42. remember previous contacts
created better velocity verlet integrator