Adds support for shader permutations and splits rendering of solid and transparent geometry into two render targets. Also...

* Fixes that SSAO was visible behind transparent geometry
* Fixes that the scene had to be rendered once more for refractive effects
* Adds support for fading of water at the shore (simple depth test when merging the transparent and opaque RTs)
* Improves overall performance due to the removal of costly shader-stuff thanks to the shader permutations