Convert Lanner to sgmodel

An sgmodel conversion of the Lanner. This patch also updates the ship definition and Intro code to use the converted model, and deletes the LMR version.

To do:

* Glow and specular textures (but I most likely won't bother doing this unless I try to completely redo the materials)
* Hydraulic rams on the undercarriage (the LMR version has these)
* Collision warning lights (these are extra white strobes)
* Headlights (aka landing lights)

Done:

* Main hull.
* Thruster positions.
* Navigation light positions.
* Basic landing gear animation.
* Collision mesh, including wheel blocks so that it sits at the correct height on the pad.
* Textures packed into one (though at 2048x2048, it's larger than I'd like)
* Material set reduced to three (shiny/matte/emissive). Given how little the emissive material is used I might scrap it.
* Fixed edge glitches. These were due to incorrect vertex normals (faces at sharp angles coming together and producing bad normals along the line of the edge).
* Pattern texture for the coloured stripe.
* Add a lower LOD that doesn't have the landing gear, and only uses one material.

Screenshots:

![Lanner 1](http://i.imgur.com/2UR86.png)

![Lanner 2](http://i.imgur.com/gYjN5.png)