Adding Geometry clone function.

Maybe someone will find a use for this. I use it to allow editing of the geometry of a cloned mesh. Note that Mesh.clone() only performs a shallow copy of reference to contained geometry, so this can be used to perform a deeper copy of the mesh object as required.
Merge pull request #69 from ChrisDenham/patch-6

Adding Geometry clone function.
Fixes extreme slowness of Geometry.rayIntersection.

You are all going to love this pull request!

It fixes an extreme inefficiency in 'Geometry.rayIntersection' caused by using the 'indices' property rather than the '_indices' member. This was making three copies of the entire index array for EVERY triangle.

Ray intersections with complex models is now actually usable.

Enjoy!

Chris.
Merge pull request #72 from ChrisDenham/patch-9

Fixes extreme slowness of Geometry.rayIntersection.
Texture LOD bias support

usage example "tex t0, v1, s0 <2d,repeat,linear,miplinear,bias40>"