Add forceUpdate flag to view.update()

[petbuc16]

When I am loading a font in the background and add it to the dom afterwards, the paper view does not recognize the change.

The function update says:

update: function() {
  if (!this._needsUpdate)
	  return false; 

  var project = this._project,
	  ctx = this._context,
	  size = this._viewSize;

  ctx.clearRect(0, 0, size.width + 1, size.height + 1);

  if (project)
	  project.draw(ctx, this._matrix, this._pixelRatio);

  this._needsUpdate = false;
  return true;
}

So add a flag forceUpdate to the function.

[sapics]

I agree that forceUpdate is necessary for updating after font loading.