Add option to set background renderer color
Register each attribute's change event individually, rather than a huge update event.

Not tested yet...
Clean up all the for loops in per-attribute triggers
Trying to load the notebook widgets doesn't work so well right now.

Since we don't actually have that file, we'll just assume it is loaded already for now.
fix children reference access before defined
fix typo in updating children attributes that prevented the three.js object from being set correctly
Merge pull request #4 from jasongrout/registerattributes

Register each attribute's change event individually, rather than a huge update event
assume widgets have been loaded already
Merge branch 'master' of github.com:jasongrout/pythreejs

Conflicts:
	pythreejs.js
add event argument to picker callback
Merge branch 'master' into picker
Make controls a list of controls rather than just one control.
We won't have a 'controlling' attribute for pickers.
Refactor the making of the ray caster so we can inspect the ray vector more easily.
Work on a bug dealing with getting the appropriate mouse coordinates.

I noticed that that.options.dom.width was much higher than the pixel width of the canvas element.  It appears that it is the difference in the CSS width and the canvas width from doing something like <canvas width="500" style="width:100px">.  The mouse click appears to follow the css width (100px), but if you do canvas.width, you get 500.  So this change calculates the width based on the mouse click coordinate and the CSS width and height (rather than the canvas coordinate width and height).

There still seems to be something wrong with some calculation somewhere---I still can't hit an object by clicking on it.  It may be related to a messed up mouseY calculation.  I'm not sure.