This allows to have different shadow map parameters for different lights, also it's easier to access parameters for tweaking / debugging.

Changes:

renderer.shadowMapWidth    => spotLight.shadowMapWidth
renderer.shadowMapHeight   => spotLight.shadowMapHeight

renderer.shadowMapBias     => spotLight.shadowBias
renderer.shadowMapDarkness => spotLight.shadowDarkness

renderer.shadowCameraNear  => spotLight.shadowCameraNear
renderer.shadowCameraFar   => spotLight.shadowCameraFar
renderer.shadowCameraFov   => spotLight.shadowCameraFov

Also added new uniform type "v2v" for array of Vector2 (to support per-light sizes of shadow maps).

This is for seeing how camera actually looks (frustum, line-of-sight, up), it's not a camera. Not sure about the name.

Fixed bug where depth buffer is not cleared if last object rendered on previous render cycle disabled depth mask.

I think dev branch should have docs corresponding to dev branch code.

Shadows should be now done more correctly and also be a bit less fussy. Before RGBA encoded depth maps were getting messed up with blending (that's why everything was extremely sensitive to frustum size).

All examples with shadows had to be re-tweaked (shadows now behave differently).

Plus added "onUpdate" callback handling also for cube textures.

This is necessary for OpenGL where pow(0,0) is undefined and apparently can be negative, leading to negative specular light (in DirectX you just get zero).

Also some more refactoring in IcosahedronGeometry and tweaks to geometries example.