Agent patch accessors, dataset updates, model isTorus default change & debug wait use.
  Note: Most of this from Stephen & Benny, thanks!
- DataSet
  - Bug fix w/ ImageDataSet formats
  - Experimental patch datasets
  - toPatchVar: return experimental patch dataset
  - slopeAndAspect: return prior values if already computed
- Util
  - Add polarToXY
- AgentSet
  - show/hide: add draw after setting hidden
- AgentSets
  - Patches: @drawWithPixels variable; isOnWorld method
  - Agent: add patchAtHeadingAndDistance patchLeftAndAhead
      patchRightAndAhead patchAhead canMove
- Model
  - isTorus default changed from true to false
  - Remove toggle method
  - reset: temporarily add console.log to monitor very large resets
  - debug: add u.waitOn to make sure all variables set