Provide a clone method to the specialized geometries in
src/extras/geometry, otherwise:
- the `.parameters` are not copied
- the `.type` of the clone is "Geometry" or "BufferGeometry"
- the cloned object is not an instance of the initial type. It loses its
specialization and becomes a plain `Geometry` or `BufferGeometry`.

Class deriving from `PolyhedronGeometry` defined  `this.parameters` all
over the place. Standardize to defining the `.type` and `.parameters`
after the `PolyhedronGeometry` constructor is called.

Also fix prototype inheritance chain for classes deriving from
`PolyhedronGeometry`.

Clear the target data before pushing new vertices and faces

Add documentation over textures not getting disposed together with material

Add scaled vector

Make BoxHelper workable with Object3D

Codestyle

sea3d demo, unnecessary container config

Clean up of sea3d demo

WebGLMultipleRenderers: Use Geometry

- WebGLMultipleRenderers: Use Geometry instead of BufferGeometry
- index.html: add "webgl_multiple_renderers" again
- Misc. fixes to please closure compiler (unused var).

Deprecate offsets in favor of drawcalls

sea3d loader example