Improved terrain system

-Improved the terrain layers blending
-Improved the grass shader
-Sun assignement on athmosphere, clouds and sea is now automatic in
preparation for the solar system generator.
Merge branch 'master' of https://github.com/MrNothing/Infinite-Universe

Conflicts:
	SandBox/Assembly-CSharp-Editor-vs.csproj
	SandBox/Assembly-CSharp-vs.csproj
	SandBox/Assembly-UnityScript-Editor-vs.unityproj
	SandBox/Assets/Assets/Doodads/Details/Materials/Bush7-Bush7Mat.mat
	SandBox/Assets/Assets/Doodads/Details/Materials/Weeds_05-weeds.mat
	SandBox/Assets/Assets/Doodads/Trees/Trees Ambient-Occlusion/Materials/scotspinetypeb-pinetrunk.mat
	SandBox/Assets/Scenes/main.unity
	SandBox/Assets/Scenes/sample.unity
	SandBox/SandBox-csharp.sln
	SandBox/SandBox.sln
	SandBox/SandBox.userprefs