Add a visual underwater effect

[emezeske]

I'm picturing an additional shader pass that performs a Gaussian blur on the full frame if the Player's eyes are underwater. Here's a couple of good resources:

* http://www.gamedev.net/page/resources/_//feature/fprogramming/opengl-frame-buffer-object-101-r2331
* http://www.gamerendering.com/2008/10/11/gaussian-blur-filter-shader/

[emezeske]

Some kind of underlava effect is also necessary. It can probably be very similar to the underwater effect, but with more distortion and an orange tint.