Add hardware node coloring. Includes:

- Increase ContentFeatures serialization version
- Color property and palettes for nodes
- paramtype2 = "color", "colored facedir" or "colored wallmounted"

src/client/tile.cpp

@@ -378,9 +378,6 @@ public:
 	video::ITexture* generateTextureFromMesh(
 			const TextureFromMeshParams &params);
 
-	// Generates an image from a full string like
-	// "stone.png^mineral_coal.png^[crack:1:0".
-	// Shall be called from the main thread.
 	video::IImage* generateImage(const std::string &name);
 
 	video::ITexture* getNormalTexture(const std::string &name);