add computer model with UV coords to allow displaying text

[mwcz]

followup to #5

The computer model we have doesn't include UV coords so we can't map textures onto it. If we get a version with UV coords, we're all set to put the console texture directly onto the screen.

If not, a backup plan that should still look pretty good is to take the temporary flat plane (#5) and give it many more polygons, then curve it. Here's an equation that's at least approximately the same curve as a CRT monitor.