GLSL unit usage?

Hi @hughsk,

First of all I want to thank you a lot for making this transformer, because I was actually about to make it and your lib saved me about 10 hours ;-)
For the little story, I've start working on [this](https://github.com/gre/glsl-transition) and I use your library in the exemple.

I was wondering if it was possible to add the support of [glsl-unit](https://npmjs.org/package/glsl-unit) to being able to minimize/optimize the GLSL code. I've used it a few years ago, and it work pretty smoothly after a few customisation.

Also I don't know how this can work with browserify, I mean how you can set options to a browserify transformer, but maybe we could enable it by default (with minification but no renaming of uniforms) if not browserify debug mode?

Happy christmas,
@gre