Adds many rendering related additions, tweaks, overhauls and fixes.

* Fixes that changing the video settings (and thus recompiling shaders) without relaunching the application was not working anymore
* Rewrites SSAO (now uses a hemispherical approach - variation of the approach used in Crysis)
* Adds a seprate 4x4 blur filter for SSAO (and an according pass)
* Changes that sunlight is applied via the deferred rendeirng path
* Adds that the chunk shader supports deferred and forward shading
* Changes that the reflected chunk scene is rendered using the forward path only
* Extends support for directional light sources
* Adds a main directional light for sunlight
* Moves shadow calculations from the combine pass to the light buffer pass
* Changes that dynamic shadows (plus cloud shadows) are only applied to the main directional light
* Adds that block sunlight gets encoded into the alpha channel of the normal buffer
* Tweaks almost all rendering settings (especially HDR rendering, bloom, blur, ...)
* Fixes that the blur shader was not considering the correct texel sizes for the given rendertargets
* Moves bloom from the post pass to the pre-post pass
* Moves vignette from the post pass to the pre-post pass
* Overhauls brightness-/high-pass for bloom
* Tweaks many rendertarget sizes and settings for various post-processing effects
* Fixes that bloom was applied to the sky
* Adds debug text for the currently active shader debug mode to the HUD
* Adds lightshafts render target to the debug system
* Fixes that the noise texture used for the film grain effect was linearly interpolated
* Adds various new shader helper methods for calculating block light (and other things)
* ...