Add model startup(), add async helpers, work on GIS, add GIS demo
models:
  add data/ dir
  add gis model
  removed <body onload ...>; use setupAndGo in script.
DataSet:
  use resample for setting patch variables
util:
  fixed() to convert float number to given precision
  removed ownVarKeys added ownValues
  add isDone flag to import Image & XHR
  add filesLoaded, waitOn, and waitOnFiles using isDone
shapes:
  removed cup image, moved to demos
agentsets:
  ABM.patches etc replaced by @breed; ABM.patch etc replaced by @agentClass
  patch draw optimized if a single color using u.fillCtx ctx
  refactored importDrawing to use installDrawing for filling drawing with existing image
model
  resetAnim renamed to resetTimes
  added startup, setting @modelReady flag managed by waitOnFiles
  move setup out of constructor
  added setupAndGo, calling setup & start, which waits until startup is done