LatheGeometry modified to use Vector2 and allowing axe choice by the
called.
The axe is designed by a letter because I didn't know where I should put
a constance definition.
The loop that create the geometry is not optimized for speed => the axis
test is in the inner loop.
Should not break any existing code.
Doc and exemple not updated yet.

LatheGeometry is a standard geometry but it's not processed by
parseGeometries of ObjectLoader.

* Shorter (less typo-prone)
* More intuitive (also "aligns" with gl.POINTS)
* Makes a nice API (Mesh, Line, Points).

issue #7103
ObjectLoader.js, method parseTextures, offset is now restored.

@qwertzui11 do you mind double-check that I didn't break it?

KeyframeTrack.trim( start, end ).  Return this if possible.  Use fps in ObjectLoader.  Add KeyframeTrack.scale()

- `AreaLight`: Add to the `ObjectLoader`.

- `DirectionalLight`, `HemisphereLight`, `SpotLight`: Update matrix in
constructor. These lights are not create at origin. The default
constructed Matrix4 is the identity matrix and is out of sync with the
actual position.

- Unit tests