Convert Lanner to sgmodel

**WIP**

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:

* Pattern texture so we can have the coloured stripe (we need the coloured stripe). Unless we just want to hard-wire one colour in there?
* 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)
* There are a few edges that show some slight glitching. I think these are parts of the mesh that have duplicated vertices for some reason.

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.

Screenshots:

![Lanner 1](http://i.imgur.com/2UR86.png)

![Lanner 2](http://i.imgur.com/gYjN5.png)