Update examples/webgl_custom_attributes_particles3.html

The result for attributes.size.value[i] can be negative which in turn makes gl_PointSize negative. As an example if Math.sin(...) returns -1 then you'll get -6 as a result. The specification specifically states:"If the value written to gl_PointSize
is less than or equal to zero, results are undefined". In fact it is causing such a problem on our platform.
 

Docs: Removed controls.

Updated README and removed unneeded includes in example.

Tweaked the cloth simulation example a little.

Fixed SceneUtils.cloneObject.

Updated r46 with some bugfixes found post release.

Beautified usage example.

Fixed mouse listeners on draggable cubes example, also reverted to pr…

…evious aesthetic (sorry @alteredq).