Fixes #5570

Before base class attributes that weren't in the constructors were not cloned properly in derived classes.

This is needed for handling manually created non-power-of-2 or small RGB DataTextures.

It corresponds to GL_UNPACK_ALIGNMENT parameter in glPixelStorei:

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

Warning: this doesn't work with RGB textures (3 bytes per pixel) because of default 4 byte alignment requirement deeper in WebGL / OpenGL layer. Uploading smaller mipmap levels gets these GL errors:

"ArrayBufferView not big enough for request with UNPACK_ALIGNMENT > 1"

It works ok with RGBA textures (4 bytes per pixel). Seems this could also explain why 1 pixel RGB DataTextures were failing sometimes.

Unfortunately we can't keep these settings always on: without "--jscomp_off=checkTypes" the amount of spam is just too crazy. It complains about tons of normal things, I had to manually dig out few useful warnings among 900 irrelevant ones.

As per @toji's "don't lie to WebGL about your format" recommendations in WebGL Camp 4 talk (http://media.tojicode.com/webglCamp4/#19).

Moved `src/materials/*Texture.js` to `src/textures/*Texture.js`

DataTexture can be used in the same places like image / video based Texture (WebGLRenderer-only).

To be used like this:

var width = 64, height = 64, bytes = 3;
var data = new Uint8Array( width * height * bytes );

// fill data array with values 0 .. 255

var texture = DataTexture( data, width, height, THREE.RGBFormat );
texture.needsUpdate = true;

For the moment only UNSIGNED_BYTE type is supported.