use node.js style require

npm publishable

use bundled dist.js instead of multiple files

bundle that may be used in the browser

use tabs
only one verlet on npm
sane gravity
browserify as dev dep
document build
oops, should be `npm run build`
better build script
build is too complicated for readme now
check in generated js files
Merge pull request #14 from dominictarr/npmable

use node.js style require