Adds various rendering related additions, fixes and tweaks. Also adds TeraEd to be a part of the Terasology distribution by default.

- Tweaks sky shader and adds inscattering (colored haze/fog) effect to the terrain
- Adds first version of light shafts (currently disabled)
- Increases water vertex animation complexity a bit
- Replaces water normal map
- Adds various new properties to be used in combination with TeraEd
- Cleans up various other things