Also added rudimentary position-based vertex colors to MarchingCubes object and example for testing.

There is no normalization or anything, it's up to application layer not to set colors beyond <0,1> range.

This addresses issue #1834

As per suggestion in https://github.com/alteredq/three.js/commit/5d5f92d6411f3d39725ea704594d7a09ecb92cca

Only these 4 are actually valid for regular textures:

http://www.khronos.org/opengles/sdk/docs/man/xhtml/glTexImage2D.xml

We had it wrong before, it just accidentally worked as default type GL_UNSIGNED_BYTE is common for both data types and pixel types.

Also added optional quick-and-dirty UVs for MarchingCubes object, just to be able to test this. For the moment these are just XZ world coordinates.

This should address half of #1834

As per discussion in #855

To be tested if it works ...

See discussion here: https://github.com/alteredq/three.js/commit/2fd0b1b14deef40825d6a853ae0522f78d4b57d8

As per discussion in #1803.

It's really hard to tell if this has any affect at all as shader creation by itself is so costly it dwarfs everything else.

This seems to work.

This should address #1803

Todo:

- write some test
- hook this into material.needsUpdate handling
- figure out what to do with GL shader objects

Still need to fix influence sorting.

Maybe we need a build/custom/ThreeCore.js though...

As per discussion in ee946579

Anaglyph and ParallaxBarrier could also be merged somehow, as the only change is the fragment shader.

See discussion here: https://github.com/mrdoob/three.js/commit/6e002f324a06f6f766b50c930732a9994fdd4ac6#commitcomment-1234473

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

This reverts commit de6d62bf.