0.6.1a voxel manipulation

0.6.1a:

 - Block now contains an onDamage and onBreak method.

 - Block now has a breakable boolean and a health double.

 - VoxelMap now contain a damageBlockAt method.

 - VoxelMap now contains a getBlockAtInt method and setBlockAtInt method which uses integer block positions.

 - Fixed scaling issue with BoxRenderable.

 - Fixed rendering issue with BoxRenderable.

 - VoxelCollisionSystem has been tested and working properly.

Bugs:

PFB-0002a, VoxelMapRenderSystem only works properly at camera zoom of 1.0;