Make data come back from the picker to python.

Here's an example:

html("<script src='http://boxen.math.washington.edu/home/jason/pythreejs/pythreejs.js'></script>")
load('http://boxen.math.washington.edu/home/jason/pythreejs/pythreejs.py')

import time
print 'Loading...'
time.sleep(2)

geometry = SphereGeometry(radius=4)
material = LambertMaterial(color='white')

myobject = Mesh(geometry=geometry, material=material, position=[3,4,5])
c = PerspectiveCamera(position=[0,10,10], fov=40, children=[DirectionalLight(color=0xffffff, position=[3,5,1], intensity=0.5)])
scene = Scene(children=[myobject, AmbientLight(color=0x777777)])
p=Picker()
renderer = Renderer(camera=c, scene = scene, controls=[OrbitControls(controlling=c), p])
show(renderer)

def picked(name, new):
    print new
p.on_trait_change(picked, 'picked')
Fix object parameters on meshes and other things that call replace_obj

This fixes, for example, the position argument on meshes.
Merge branch 'master' into picker

Conflicts:
	pythreejs.js