Headless: either untimed or via rAF.
- Update to latest coffeescript/docco
- Model: modify headless interface slightly
  - Remove headless from ctor, default to world.isHeadless
  - Ctor multiStep defaults to isHeadless
  - Fix anim headless to allow either setTimeout or request anim frame
  - Adjust Model to changes
Note: goal is to have simple parameter scans in future builds.
DataSet.slopeAndAspect now returns an object instead of an array.
Updated droplets.html to reflect this change.
Model div h/w set; gridpath fix; Util downstep image
Model: set layers div size for css use.
Models: Gridpath model's label text fixed
Util: Add imageToCtxDownStepped: (img, tw, th) -> # http://goo.gl/UnLJSZ
ABM.Model constructor now accepts a world object.
Updated example models to use new constructor syntax.
Merge remote-tracking branch 'upstream/master'
Merged with upstream/master.
Fixed a bug with headless models using patches of size 1
Reverted unrelated package.json commits.
Reverted package.json commits.
Merge branch 'slopeandaspect'
Merge branch 'world-object'
Merge branch 'headless-patch'

Conflicts:
	lib/agentscript.map
	lib/agentscript.min.js
Reapplied reverted commits from package.json branch.
Commiting after a build.