Not sure if this should be enabled by default though.

This should fix doubleSided objects causing misbehaved shadows reported in #1758.

It's now done once per frame / plugin instead of per material.

Fixes #1757

That wasn't supposed to go in...

I tried to move BinaryLoader to /examples/js but SceneLoader needs it.
Curious to hear what people thinks about this change.

That was a tough one: spotlights were randomly working / not-working based on completely unrelated stuff.

This adds 2 extra parameters to SpotLight:

- "angle" for controlling light cone width
- "exponent" for controlling sideways light attenuation (from light->target axis towards edges of light cone)

Warning: this changes appearance of everything that used old fake SpotLight. To get approximately similar look use these parameter values:

```
spotLight.angle = Math.PI;
spotLight.exponent = 1;
```

Todo:

- implement spotlights in normal map and skin shaders
- check what's going on with vertex colors and ambient term in unlit parts
- check shadowmap darkening vs unlit parts darkening
- maybe some better formula for light cone attenuation, current one varies too wildly with cone angle

(Phewww!) I'm sure there are still things I missed...

Commented out WebGLRenderer console.log (not really useful anymore) and added new console.logs on all renderers (hopefully more useful).

This is now done as method of Matrix3 object which gets as a parameter Matrix4 object to be inverted (to be consistent with how Matrix4 => Matrix4 inversion is done).

As per discussion in #1615.

Added CustomBlending mode. Added texture.premultiplyAlpha parameter. Added standard and custom blending examples.

Thanks to @toji for the suggestion.

This probably could be done in some nicer way, but at least there is no more direct dependency in WebGLRenderer (and lib shrunk ;).

Set WebGLRenderer's default precision back to 'highp'. Added specifier to vertex shader too. Fixes #1602.

Set it to "true" to rebuild the shader.

As per discussion in #1534

Issue 1: when having multiple ParticleSystems, starting since second one particles got sorted according to wrong matrix (it was cumulating all transforms).
Issue 2: particle sorting was using camera transform from the previous frame.

This commit is scary, lot of potential for something getting messed up in a subtle way.

This fixes issue #1504

Something similar would have to be done in Projector.

Also while at it I found particles sorting is incorrect: it uses camera info from the previous frame plus _projScreenMatrix gets multiplied more times when there are more particle systems.

Also some shaders refactoring.

Still todo: doubleSided handling for reflections / refractions.

As per discussion in #1324