[WIP] Transparency

We should have done this earlier....
Here comes Order Independent Transparency using Weighted Average
Because we use instancing etc it was not possible to directly use the glow implementation, but most is stolen from there.
With two render passes and one additional render target, you get transparency for any Voxel in a VoxelCluster and any Particle
Please try this ASAP and be blown by the awesomeness :smile: