Nonlinear scanner

Tired of being jumped by pirates because your scanner was zoomed in and you didn't see them?  Want to zoom in on a close adversary in a dogfight without losing track of more distant ships?  Then you need the new nonlinear scanner!

Based on captured Thargon technology, and extensively re-engineered by Faulcon de Lacy skunkworks division so you don't need compound eyes to use it, the nonlinear scanner is the answer to every pilot's scanning problems.

Here's how it works.  In the below screenshot I've just zapped an asteroid, and want to zoom in on the splinters to scoop them up.

![scanner1](https://f.cloud.github.com/assets/5890866/1830164/8485c078-7328-11e3-9328-5d4d8a647702.png)

Normally, I'd lose track of the ship lurking in the corner of my scanner.  Not with the nonlinear scanner:

![scanner2](https://f.cloud.github.com/assets/5890866/1830166/d22c28bc-7328-11e3-81bc-0e69e9014d2c.png)

The ship is pushed towards the edge of the scanner, but is still visible on it.

Enabling the nonlinear scanner is a simple matter of setting nonlinear_scanner = yes in your hud.plist.  I've also added an ultra_zoom option to the plist which, when set to yes, gives zoom levels in powers of two, up to a whopping 16:1 - perfect for picking up that awkward bit of cargo.