Initial import of Preetham Sky Shader and Example
Added Raycaster support for THREE.PointCloud
Add SVGLoader. See #4429
OrbitControls handles mouse moving outside of window

OrbitControls will continue to follow the mouse position even after the
mouse button is up, if the user moves the cursor outside the window and
then releases it. The user must then click again inside the DOM element
to release the mouse tracking. See, for instance, the OrbitControls
example (http://threejs.org/examples/#misc_controls_orbit).

This can be fixed by attaching the `mousemove` and `mouseout` handlers
to `document` rather than `domElement`. This fix works on
Firefox 27.0.1, Safari 7.0.3, and Chrome 34.0.1847.131, on Mac OS
10.9.2.

Alternatively, the example could be changed to not pass a value for the
`domElement` argument, to get the default value of `document`.
Set OrbitControls polar angle limits to [0.01, pi-0.01]

OrbitControls suffers from gimbal lock: if you rotate all the way to the
north or south pole, it will feel 'stuck' in the east-west direction.
This patch fixes the issue by setting the default minimum and maximum
polar angles to 0.01 and pi-0.01 radians, which eliminates any
perceptible gimbal lock effect at ordinary browser frame rates.
Add a touch of damping to OrbitControls

Inspired by damping in TrackballControls, adds a little bit of kinetic
friction to OrbitControls. This makes the rotation controls feel much
more physical.

Damping is disabled by default, preserving the existing behavior.

Damping is enabled explicitly in the example.
Dolly translates camera rather than scales its distance

At least on Macs, trackpad swipes already trigger a sequence of
mousewheel events with smoothly damped deltas, continuing after the
fingers have been lifted from the pad. Unfortunately, the intuitive,
smoothly damped dollying motion that this would cause is canceled by the
exponential zooming behavior (multiplying or dividing the current
distance by a fixed value).

It feels much better to dolly in and out in a linear manner, as this
patch does. The change is especially noticable if
(maxDistance-minDistance) is finite.

Note that different browsers produce mousewheel deltas with different
scales. This patch copies some code from TrackballControls to normalize
to a common scale.
Merge branch 'orbit_controls_mouse_outside_window' of https://github.com/lpsinger/three.js into dev
Merge branch 'smoother_orbit_controls' of https://github.com/lpsinger/three.js into dev

Conflicts:
	examples/js/controls/OrbitControls.js
Merge branch 'dev-particles' of https://github.com/WestLangley/three.js into dev
Merge branch 'svgloader' of https://github.com/zz85/three.js into dev
Added interactive pointcloud example to examples list.
Updated builds.
Merge branch 'sky_shader' of https://github.com/zz85/three.js into dev