Unstable branch updated (v13 preview)

Hi!

The current set of changes are now stable enough for the unstable branch. Let's celebrate with a piece of cake. :P

Current list of changes:

// Hit distance for bugs is now same as building distance.
// Improved sky lighting.
// Corrected snow covered grass color
// Better texture and normal maps for snow and sand
// New poly tool. Select 3 or 4 points and hit [Enter] to fill.
// Crafting time is now shorter.	
// Fixed scaling of plant tool icon in inventory.
// Cliffs. New world feature. Can be disabled in "New game" options.
// LOTS of rendering optimizations. 
// LOTS of Worker logic optimizations. 
// Added stone tool.
// Scalar field voxels super smoothing. 
// Some floating blocks will now sunk into soft materials.

Best regards Jens